4sevens has given a great explaination of why the QAA is about half as bright on 1.5 volt AA batteries. The Q123 is smaller and runs full blast on one lithium cell.
But, your logic is persuasive, put in a 14500 for full regulated brightness and have readily available AA's as a backup...:twothumbs
VOX... I love Li-Ion powering for flashlights and if a light can run on Li-Ion, that's generally my choice of powering, so to my way of thinking
the Q AA is a 14500 Li-Ion light and
the Q 123 is a 16340 Li-Ion light, even though both will also run on primaries. In this way I view them as comparable Li-Ion lights. Output is the same and runtimes are very close. They differ in length and the versatility of clip reversal/removal.
The option of being able to run lithium primaries, NiMH rechargeables, or God forbid, alkalines, if necessary, is a wonderful extra benefit of choosing the Q AA that the Q 123 doesn't offer. But since I also have and really like RCR123/CR123 lights, I just ordered a Q AA complete light and a 123 body to allow numerous powering/profile options as desired. That's just how I would want it to be. And when the tactical switch becomes available, I'll add one of those to the "kit" and be happy as a clam! :thumbsup: Not sure whether I'll use my light more in with the AA-size body or the 123-size body.... time will tell. But as a standard, I will be powering it with Li-Ion, either 14500 or 16340. I keep a good supply of long-life lithium primaries (L91, L92, and Panasonic CR123) in the fridge, and some Eneloop NiMH cells, but these are secondary powering options for me... just as back-up/emergency use cells.