Just my 2 copper pieces:

CCW: If you mount a light onto your CCW, you need to take a look at the size increase of the holster as well. Its an overlooked aspect. The over all package gets big real fast with a mounted light. Also, look at the burn time of a rail light vs. even a small AA EDC type light.
Bought a few of Fenix LD11 G2 LED Flashlight - Fenix-Store . and so far they are great little lights, single AA, 14500 compatible, good multiple power settings...did I mention Single AA!

No holster: would not do buddy. Revolver stuffed in a bag, sure, Glock...nope.

*Dont get me wrong, I love a rail mounted light, just not on my CCW.