CR123 batteries HAVE come down in price - a LOT - check out Surefires price on them - I think it's about $1.50 now

6P - pros - more accessories, and you can get the High Output Lamp Assembly
Cons - Larger than the E2E, more expensive

E2E - pros - smaller, lighter less expensive. The "standard" bulb is about the same brightness as the Low Out Lamp of the 6p - that said, you can get an even lower output lamp - much longer run time

That said - I no longer edc my E2!!! (Not E2E). I rarely need that kind of throw, and it was my only unit that NEEDED CR123s. I've switched to an ARC-LS LED light with a 2AA pack. The main reasons for the switch? I'm trying to get down to 1 type of battery for my edc. I love my E2, but it sits on a hook next to my rear door if I really need it