I have both 6Ps and E2 SureFires. I daily carry the E2 due to size and have my 6Ps now reserved in my CERT kits. I have both 120 and 60 lumen lamps for the 6P, but be warned it eats a set of batteries in 20+minutes at 120 lumens.

I have the NiCad pack and extension for my 6Ps which I use when I know I want a strong light for a known purpose, these do not work as storage lights though as the packs discharge over time.

I also carry an Inova X5, which also takes CR123A Lithiums and it is my preferred light for most uses. Plenty bright, conservative of the batteries, waterproof and durable.

My E2 is reserved as an escape light carried On-body. I prefer the E2 to the 6P as a carry light that is not used much but carried for emergency use.