Besides the usual cautions of using the same brand and capacity cells, is there any real danger that I should know about if I decided to stack two 16340 IMRs as compared to two ICRs?
Just the usual, IMR’s pack a tremendous amount of power and can discharge really really quickly.
IMR’s are also most likely non-protected, so watch out for voltage differences when discharging ie) 3.0V vs 3.3V and make sure you take them out before they become completely discharged.
Other than that, they’re pretty much the same as ICR’s. Cheers.
Thanks for the reply. I figured they were OK, but it never hurts to check. I’m very cautious about matching cells, and I’ve never tried 2 X IMR.
Yup, better safe than sorry. I use 2x AW 18350’s in my laser, and everything runs fine as long as I don’t over discharge them.
I did that once but quickly charged them up again. 
Coincidence? 2 X 18350 AW IMR is what I am planning to buy. No reason in particular, I’ve just never had one.
16340’s are very common, but we do prefer 18350’s for its higher capacity and snug fit. 
What application are you going to use? Interestingly enough, I found 18350 Ultrafire’s to have higher capacities than AW IMR’s.
If you don’t need the high current, I’d use the Ultrafire/Trustfire cells and save some extra $$. (Go BLF!)
I’m really not sure at the moment. First I’ll go through my lights to see which ones they fit, then check if there’s any noticable output benefit. Once I have them I’ll probably get a solar force host and look for a drop in that can use the amps.
Watch out for driver burnouts.
I did have some LED + Driver sets go poof with the extra voltage.