So a top end carbon frame is less than half the weight of your titanium frame. That's not inconsequential...

No, that's not right. Lightest carbon frames weigh in the neighborhood of 700-800g. Still more than half the weight of a fairly light titanium frame. There are much lighter titanium frames, however. They are just much more exotic and less common than the 3+ lb variety. But fractional comparisons are not as important as the absolute weight difference. It is probably reasonable to assume that lightest carbon is about 1 lb lighter than lightest titanium. Significant but not earth shaking.

Lightest frame currently is Cervelo RCA at 620 grams bare frame.

Is 1.5 lb substantial?

Litespeed used to make 750 gram frames but those were noodly as all hell and pretty fragile too, so let's focus on actual dependable usable frames with an acceptable stiffness. In that case, there aren't many ultra lightweight titanium frames

Yes, the Cervelo Rca is $10K though. A $10K Ti frame is going to be light as well.

combine the benefits of carbon and ti ... I love mine

https://www.hollandcycles.com/

No it isn't

My Calfee doesn't feel dead at all. The thin round tube on a Calfee makes it a very lively frame.

Well, the Rca is going off on a wild tangent.
Rca? That's comparing apples to the space shuttle. Not many of us here could afford the space shuttle.
rpenmanparker, when you get time I would like to know how you spec'd your Everti Falcon.
Looking to do a custom build, 14lbs would be more than adequate for my needs.
OP, can't go wrong with either frame types if you do your homework.
Personally like all of it. Specialized Venge is sweet (even though a poster
here equated the look of the Venge frame to that of a dog taking a dump! harsh, it looks good to me).
The Cannondale Evo Red was on sale last month for $3,650. Wow.
Looking at SRAM Red group at Glorycycles for about $2,500 for my build, a grand more you can get a whole bike! https://www.cannondale.com/supersixevo-springsale
Carbon bikes from Focus and others give carbon an edge.
There are some Ti frames coming online from Merlin, Lynskey and even Soma that
are cheaper than full on custom Ti, but carbon wins the light weight/value war unless you do some digging
and spend some money to get the numbers right. Can be a close race.
My solution is to have both. Not going Ti though, going custom lugged stanless steel.
Then will pick up a carbon bike a few years later. The way prices are going for carbon, the over seas stuff especially,
by then a feather weight/well spec'd ride will be within easy reach.
As far as ride, feel, it's like saddles OP, only your butt can decide what is "best".

You guys are stealing the OP original intent, he is asking about the ride feel, not frame weight.

That being said OP have you tried getting a fit? That could help. It also sounds like you almost have everything dialed in but not quite, and it seems like you're a millimeter man, very in tune to your ride so you Foil is just a little off. Going custom might be your answer, first you would get a fit perfect your body measurements but you would also be able to give customer frame builders what kind of ride quality you want i.e stiff and light or comfortable and relax, heck you could tell them what your "dream ride" is and they can figure out what frame you need with tube diameter, wall thickness and tube selection. Good frame builders would be Independent Fabrication, Moots, Alchemy however down side would be wait time depending on the builders. Hope that helps you out.

Weight has no relation to ride feel? Interesting

Arguing about carbon frame weight vs Ti has no relation.

Out of the saddle, frame weight doesn't affect the way the bike feels? interesting

Yes, you are quite correct. I have been trying to dial this bike to get it as good as i can.
Saddle height and position is crucial and mm's change more than i could ever imagine.
But somewhere the handlebar must be aligned it these changes and that is also a bit tough working the fit alone.
It is not impossible to get the Foil to be bettered,... but i can't progress more on the Foil frame (and size) that i have.
I've noticed many claim the design (optical) of the frame will alter the ride feel. Lately i have been wondering if the carbon layout, resin and structure also need to be designed for a more damped, absorbing and more vertical compliant behaviour.
Bianchi Infinito CV seems to be closest to actually make sense in this specific area.

Worst case scenarios is if the titanium platform would be to much of a change (trade off).
I have been in contact with quite a few custom builders. I'd need a custom fitting first.
For me that equals a long travel and all in all very high cost (I am in northern EU).

A manufacturered frameset would be more in range of what i might be able to finance and i believe that there is a high possibility to find what is a deal braker.
Thanks for the input

Sounds like you bought the wrong bike. A Scott Foil is one of the stiffest bikes on the market...perhaps thee stiffest. Those that purchase such a bike want the ultimate aero speed machine. Pcad has one and says he doesn't care about the ride and its the best and fastest bike he has owned. He wants the fastest bike and that is what he has. There are a lot of Specialized Venge bikes on ebay for the simple reason that many don't like the ride. Some prefer this ride as they know this kind of road feedback is going to provide the fastest bike with no wasted motion. The Tarmac is a more compliant yet still a stiff bike that climbs better. But it won't cut the wind quite as well as either a Foil or Venge. Comparing any Ti bike to the aero Foil or Venge is like comparing a Lincoln to a Porsche....Lincoln will be heavier with better ride and be slower.
Designers have more latitude to create a variety of different ride and performance qualities with carbon versus more uniform frame section Ti. Also Ti is homogeneous and Carbon isn't...latter can be laid up in different directions to create differential flex modulus. Latter sentence will escape many but is critical to why carbon is such a great material.
So OP...if speed isn't your priority, then maybe a Ti bike will serve you better. I personally don't want to ride a Foil everyday with its aggressive geometry and uber stiff ride. I wouldn't own a Venge either. But...there are plenty of great carbon fiber road bikes on the market with fantastic ride quality and greater differential stiffness than a Ti bike...I own one.

I don't have a carbon bicycle, but I do have a titanium ... and I like it. I had wanted a titanium bicycle for years, and finally acquired one in 2010.

There are two really good replies to the OPs question - Campaq4life's (which just about all his posts are informative and helpful) and this one from the beginning

Campag4life, this is why i mention titanium and trade off. I don't wish to trade off speed. Speed and being better/ faster, more technical aswell as buying a bike helping me to be a better rider is top prio. If a bike would feel slower, or i notice i am slower, i would go bananas and bike would not be used (this i am sure of).
This is why i feel i'm putting up a bit of a difficulty in asking these questions. Quite often i am told i need to do this "trade off", if i am buying the comfort i also buy the slower bike.
I am not so sure.

I have been working long to get Time bikes race and performance fit frames stack and reach (Medium and large frames), but not even Time can supply these figures.
So the folks at Time asked me to come to France to test ride Fluidity, NXrs etc etc. Sure it would be a dream.
But i can't afford this.
Thanks to all for inputs

^ it's as accurate as the Park Tool scale. I also weighed it with a fishing scale and got the same weight. At most there could be a small calibration error.

Wilier actually guarantees that each Zero 7 is under 800 grams, weighs each frame and certifies the weight.

Depends on how the bike is built.

A round tubed, Ti 3.5/2, is going to be compliant and bump absorbing.
A shaped and oversized, Ti 6/4, is going to be uncompromisingly stiff.

A Carbon Specialized Roubaix is shaped to flex, with rubber inserts to absorb vibration and bumps.
A Carbon Specialized Venge is supposed to be an uncompromisingly stiff sprint machine.

See how your vague question is unanswerable?

Talking weight.

I went with a compromise. More compliant Ti alloy, but well shaped for stiffness, a comprise of the two. It felt less chattery than even the Roubaix or Domane... but test rides are bogus. Tires, wheels, saddle are all different.

My Ti bike with pure Ultegra as pictured with blinky, pedals, etc. hovers in upper 17lbs. I want to say 17.8, but that was taken and weighed over a year ago now.

Friend's new Carbon Trek Domane 5.2 with Ultegra was "around 18lb", I'm hoping low 18s for his sake. But was $2K less. If you'd spent the extra I spent on Ti, I could have had an even lighter Trek 6 or 7 series. I'm quite happy with my Ti bike.

In response to question about spec for my Everti Falcon:
Ritchey Pro fork (350g as cut)
All SRAM Red (2010 or thereabouts) except for
FSA SLK-Light crank (same weight as that version of Red)
KMC X-10 SL chain (lighter and quieter than Red), and (uh-oh, here it comes)
Zero Gravity Ti brake calipers (65g savings over that model Red).
Terry Falcon Y saddle (227g)
Performance Pro carbon seat post (150g, no longer available)
Kestrel EMS Pro SL carbon handlebar (~180g)
FSA OS98 110mm stem (~105g)
Wheels (1,290g including tape, without skewers): Kinlin XR200 rims, BHS lightest hubs, Revolution spokes, alloy nipples, 20/24
Asian Ti skewers (45g/pair)

Considering how much lighter new Red is, you can do even better or beef up the wheels a little and still meet the weight that I got. Also with lighter Red brake calipers, the Zero
Gravity calipers may be unnecessary. You will have to search for a seat post as light as the discontinued Performance one. The Kestrel bar is a bit flimsy. You may not want to risk that.

I hope this helps.

C4L, everything you say about carbon vs. Ti is correct until you suggest that Ti won't serve if speed is the priority. Allowing for the ultimate in carbon vs. Ti design, how much "speed" could be lost with the Ti. Let's say equivalent comfort with whatever weight and stiffness penalties that entails in the Ti. I will give you that. But what speed difference could that make? I am not talking about the feel of speed in response to pedaling. I am talking about measured time performance. Are you saying Ti can't win a race? Or that the ultimate carbon bike will always win the race? You know that isn't true. These two bike would be so close in speed and acceleration performance as to be virtually indistinguishable for any but the top few racers in the world. Not in feel at the BB, but in actual velocity performance. I contend OP would be able to ride such a Ti bike just as fast (unmeasurable difference for all practical purposes) as the carbon. All that stuff about taking off like a rocket is just marketing and editorial hype.

I had my Seven (more relaxed) and Merlin (more race oriented) for many years and really enjoyed them until I bought a Cervelo RS in 2008. I can't quite tell you the exact reasons, but a combination of weight, road feel, and handling just made me want to ride it more for all occasions. I kept the ti bikes around for awhile thinking that I would use them for touring or relaxed commute, but when I woke up in the morning and picked a bike to ride to work, I was inevitable drawn towards the Cervelo. I sold both ti bikes recently.

In the mean time, I also upgraded the RS to a later model R3 (marginal improvement in certain areas, and downgrade in other areas, in my opinion), and recently built up a Cannondale EVO hi-mod wtih Ultegra Di2 (under 15 lbs). With more than 500 miles on the new Cdale, I can say it's definitely stiffer and feel very different than the Cervelo. I think the difference between the EVO and Cervelo R3 is greater than that between the R3 and the ti Seven. I am not sure I would ride the Cdale all the time.

Another bike I still have is a 2006 Lemond Versaille with carbon/steel combo frame. In theory, it was supposed to be the best of both worlds, but it ended up, for me, the worse of both worlds: stiff and soft in all the wrong places. It hangs in my garage ceiling collecting dust.

Just checking, that's all. I can't explain the weight difference in completed bikes you suggest. My bikes were weighed on a similar shop scale. My complete build is above.

Not really. You're running into the limits of the material with Ti, that throwing money at the problem won't change.

Higher end Ti frames, particularly ones that would begin to approach the stiffness of a Cervelo RCA, still weigh around 1250 grams, e.g. Lynsky Helix.

Really expensive Ti frames get you custom, not necessarily light.

Besides you can get in the 700's with CF for way less than $10,000, for example C'dale EVO.