I was looking at the Fenix L2D Q5 since it has been praised throughout, but my friend recently purchased a Fenix P3D and that thing is BRIGHT! I checked the specs on it and it's 220 lumens compared to 180 on the l2d. It's also more compact, but requires cr123 batteries.

what makes the L2D so special?

Any P7 will be brighter than any Fenix. Cheaper, too. As usual, I'd rec this one.

Link above does not work. Here is one that will work to the same flashlight.
https://www.dealextreme.com/details.dx/sku.13060

Cree has a new LED to compete with the SSC P7 and DX just posted an MTE flashlight that uses it.
https://www.dealextreme.com/details.dx/sku.16500

I carry one of these in my bike bag for night rides. It cost $10.00 and puts out a lot of light. I would buy another one if I lost this one.

https://tinyurl.com/3zvds8


This looks like the same light but for less money.

https://tinyurl.com/4b795y

On turbo the P3D will not run as long as the L2D. The P3D may get too hot on a hot day on turbo. Both of those lights recommend only running them on Turbo for ten minutes if it's a hot day. I don't think the L2D will be so hot, this is better for long term LED life. The 123 batteries can be dangerous if not handled properly. The rechargeable AA's are less trouble than the rechargeable 123s. Even though they can be found on line, lots of people don't search well and can't find 123's that are inexpensive, they mistakenly think the price of the local store is how much 123's cost (maybe $12 each). It's not true. But AA's might be easier to find on the road if you need some. Some people may already have rechargeable AA's and an AA charger.

The L2D is not special. But it's a reliable, well made, well thought out product. But, so is the P3D. So are lots of others.

Someone should buy that new 8-mode and compare it to the P7. I'm guessing the light output should be the same or slightly brighter.

I think output wise, the MC-E is going to be pretty much identical to the P7 for most cases, but the P7 can be pushed a little harder. The MC-E does have a couple features that make it more useful in some applications (such as individually accessible dies).

I got two Surefires and surefire knock off made by Pelican for free on my last trip to Iraq.

The MC-E available at DX uses a parallel connected board but Cree shows a series connected board as well. That one would work perfectly for a dynamo driven light. The Cree MC-E emitter dome is the same size as the XR-E so standard single die optics will work just fine. From the Lumen/current chart a dynamo driven series connected MC-E should be around 500 lumen with a standard 6-volt 3-watt (500mA) dynamo using Martins 4 LED circuit. I sure hope DX makes them available. They should as nominal driving voltage for battery applications of series connected MC-E LED's would be 14.8 volts, perfect for automotive applications.

Up to 2.4 hour runtime with good AA cells, for one thing When people are deciding between the CR123 and AA lights, the runtime advantage of 2AA is usually the tie-breaker. You can safely run the L2D Q5 on Turbo non-stop as a bike light.

another vote on the P7

I use my P3d on turbo in excess of ten minutes all the time without any problems. I'm usually cranking it between 30-50 minutes at a time. I must admit though that it accidentally turned on one night when I left it in my front pocket and things got a bit heated down there.

I haven't tried most of the new DealExtreme flashlights, and I'm sure a lot of them will be great bang for the buck, possibly better than what Fenix L2Ds offer.

However, I do think a big consideration that often isn't mentioned is the high build consistency of the Fenix lights. They're super reliable, built well, and if you do manage to get a defective one, you can get a new one within a week from Fenix. Dealxtreme is known to have the more than occasional oddly shaped part or thread that may or may not give you headache down the road.

For something mission critical like consistent night riding, I'm more than happy to pay a small premium for the quality and consistency that Fenix seems to have offered to the hordes of users on these forums.

The use of conventional AA batteries

that's why people are so "fascinated" about the Q5, since it cost way less that other Brand name products that cost $100+ for the same lumen

but as mentioned already, if you don't mind getting special batteries and charger
a P7 will kick the crap out of the Q5 and then some

Sure about that? I have a 600-lumen light with a fairly floody beam (namely, a DiNotte 600L), and my ~270-lumen Q5-powered Dereelight DBS kicks the crap out of the DiNotte in actual use. The reason it's better, is that it actually gets the lumens to go where I want them (straight down my lane), not spraying them all over the place in a flood pattern for "wow" effect. At this point, I don't even bother taking the DiNotte 600L along anymore. It got voted off the island

Runtime's pretty good on the DBS too, about 1.7 hours, long enough for me to actually get all the way home, instead of just partway I now have an R2 pill on the way for even more output. Probably about 300 lumens

Be carefull, if you get those batteries too hot they can explode, or vent dangerous (life threatening) chemicals. I would guess from what you said, that riding with air flowing over the light in the cooler night hours, it should be OK. The problem of overheating the LED's is that you reduce the life, and you may not notice any symptoms for a while. You might go from lots of years of life to just a couple of years of life. Not a huge problem considering the reasonable price of a new light. But, it might only last a little while longer.