I'm gonna bump this great review / thread up. After using a Ti Firefly both bedside and another on my keyring for the past 6 months, I find that, IMHO, it remains one of the better values in AA or AAA lighting. I have T10s also (AA) that I also really like.
I have more of these sitting in backup stock () than I'm willing to admit, but the 2 I have been using are still on the same batteries - simple Duracell alkaline. When I walk my dogs I'll typically carry a brighter light - or for EDC I might carry a single 123 factor light like a Haiku or the new Jetbeam TCR1, but should the battery die on one of these, the Ti is always at the ready.
The only single AAA light I like more is the outstanding Mako flood, but it's a different 'animal.' Designed with low levels, amazing regulation, long run time, etc.
But day in, day out, there's a Ti Firefly on my key chain, and it has continued to impress. Just sayin'...