The Energiser Lithiums Ultimate AAs are rated at 3200mA @1.5V though.

Personally I don't see an advantage going to CR123s from AAs if using Energiser Lithiums Ultimates as the AA flashlight can still be used with Alkalines, NiCd, NiMhs etc all with varying degrees of performance. The way the flashlight regulates the LED could be another matter though but this is highly dependent from one flashlight to another.

The Fandyfire UV-S5 that I recently purchased (makes for an excellent ceiling bouncer) will have a energy capacity total of around 40-45 Whrs and will give a similar output to a domestic 100+W incandescent bulb for about 2hrs.. or around 3-400 lumen for about 10+ hours.

Although 18650 Rechargeable Lithium Ion's are restricted to the cells that you already own in an emergency the higher rated cells such as the Panasonic NCR18650A cells will give 3100mA @3.6V = 11,160mWhrs

Panasonic NCR18650B is also available but much more expensive giving 3400mA

So a comparison;

CR123a - 1550 x 3 = 4,650mWhrs
AA lithium Primary 3200 x 1.5 = 4,800mWhrs
NCR18650 = 3100 x 3.6 = 11,160mWhrs

Another flashlight that might be of interest for area illumination tasking work, which looks to have a very good form factor size to Cell capacity ratio combined with fully adjustable output upto 200+ Lumen.

http://dx.com/p/uf-h3b-cree-xr-e-q5-230l...-x-18650-122182