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Ride them both. Then decide for yourself.

imho, once you reach the current 10spd level of components the frame and wheels are the bigger deals.

specifically with regards to the SS vs CAAD, you need to ride them both before you decide. you might actually prefer the CAAD over the SS, a 105 caad with a set of nice aftermarket wheels would be a good ride that will last you a lifetime if you take care of it.

edit - disclosure, I'm considering a caad10 ultegra this year vs a 105 evo. will ride both and see which I like best.

Frame and wheels than groupset

Importance if you're racing or just a recreational rider? As a recreational rider I'd be more concerned with the frame just because I want whichever one is the more comfortable ride. How crisp the gear changes are wouldn't concern me much since I'm not elbow to elbow in a pack fighting for position. If my shift is off a bit it's a nuisance. If 105 weighs a few grams more than Ultegra oh well. But if my frame doesn't allow me to ride as far as I want in comfort, then it's a much bigger problem.

I guess I could have elaborated, but you may find you have a strong feeling on the Sram or Shimano shifters.

Also, your intended use may play in to it. The CAAD is a popular crit bike and for that kind of use you may prefer it's ride over the SS.

I just don't buy into the "X is more important than Z" as an overall philosophy. There are a lot of preferences out there that can influence a decision, and those are all nice bikes.

Components are easier to upgrade a bit at a time, so I'd go for the frame and get the SS

This, exactly. If you get a hankering to upgrade derailleurs or whatever that's an easy job. If you decide you want to upgrade the frame, that's considerably harder.

I think most people will be better off with the Supersix with lower end components than the CAAD10. There is neglible difference in performance, but the SS will be more comfortable. Carbon is very good at soaking up very small high frequency road vibrations .

CAAD10 with 11-speed, without a doubt. That's what I should have purchased rather than my POS.

I recently ran into a bloke who had just upgraded from CAAD10 to SuperSix and he could not heap enough praise on the SS, saying the ride was a lot smoother than the CAAD10. If I was looking for one bike only, I'd probably choose the SS over the CAAD10 - knowing what I do now. I'm happy with my 2 x CAAD10s, as I wanted two identical bikes - well, apart from crankset and groupset...lol

cheers

Get the 105 bike.

Save 50 bucks a month for 6 months, take the 105 off, sell it, and buy yourself some Ultegra stuff if you're unhappy with 105 (you wont be.). When you're thinking about components, always remember that the Dura Ace of today is the Ultegra of tomorrow, and on down the line. Once you're in 10 speed territory the only real difference you'll notice is some ergonomics and weight, which isn't much. I have a bike with current model 105, and did at the same time have a year-old Ultegra groupset on another bike. Little to no difference in shifting or braking quality.

+1
If you enjoy longer rides, the vibration dampening of a carbon frame is something you will appreciate. The only concern is if you do start racing, the likelihood of you crashing and the resulting damage to a carbon frame vs. aluminum is something to think about, since you'll likely go down eventually. There should be some very good deals on the 2013 leftovers right now, so don't limit your selection to just Cannondale. Keep an open mind as you look around and visit as many shops as possible.

Echoing what others have said, the difference in frame material/design is going to have a much larger impact on your experience than the minor difference between ultegra and 105. Whichever one you end up with, make sure you budget for a session with a reputable fitter in your area, it'll make the money spent on the bike go much further.

Carbon is probably easier to repair than a crushed/bent/cracked aluminium tube. Welding a damaged aluminium frame would require skill and there is a chance the weld would fail again.

I have 105 on one bike and ultegra on another. Really can't tell much difference between them.

FWIW, I noticed a big difference in ride quality when test riding the SS and CAAD10. The SS climbs like a mountain goat. Living in the mountains, this was what made my decision. Looks like you got great tips for your purpose.

Any crash that would break a carbon frame would break a frame made from any material.

I know this isn't road bikes, but I think it makes a point.

https://youtu.be/xreZdUBqpJs

I think it's even more than that, meaning that the Ultegra of today is even better than the DuraAce of yesterday. (And the Ultegra of tomorrow will be better than the DuraAce of today)

Think Ultegra 6800 vs DA 7900.

Frames are really where the $$ is. Most bikes come with "lesser" groupsets and wheels. The 5700 105 is a great set BTW, save the brakes (which I recently swapped to 6800), I have no issues with mine what so ever. With some tuning, everything dials in well and shifting is great.

With my Tarmac, I found the wheels, brakes, bar tape and stock FSA chainrings so be lacking. The saddle was not a good fit for me, there was nothing wrong with it, I just didn't fit me well.

so...long story short. Invest in the frame and change what you don't like over time.

I have a 2011 CAAD 10 with Dura Ace and a 2012 Super Six with SRAM Red. My Madone 3.1 has 105. I notice little difference between the DA and 105. I prefer SRAM. Have a 2009 Project One with Rival.

Love my CAAD, would not trade it for the SS and vice versa. The CAAD is my only aluminum frame and is noticeably buzzier than the SS but it's a nice buzz.

Hope this helps.

Carbon is made in an oven under pressure.... all carbon "repair" is a lick-and-stick tape and glue over your frame. Once cracked, always broken.

If you are racing go CAAD. Most likely you'll fall down (a whole bunch) You'll be pretty upset when your new bike is broken because some a-hole hit you.

If you want to enjoy recreational riding... get a carbon bike.... if you are going to race next to some guy who will "do anything to win".... ride titanium. (or AL)

I think frame is more important than groupset, but you should take a look at the wheels being sold to you too. Wheels make a difference, so make sure the bike you buy has decent hoops or you save some of that budget for a good aftermarket set.

It's all about money when you are on a budget. If the bike that has the frame you prefer is going to need a new saddle, bars, crankset and wheels compared to the aluminum, it would be a better buy for you to pick the aluminum framed bike, IMHO. Just like components, frames can be replaced later on.

buy the best bike you can afford. you'll probably upgrade the components later anyway