"I mean - 3 AAA's (as opposed to 2 or 4)? What do i do with the extra one?"

Uh... buy six and have a spare set?

I agree with you on standard sized batteries for the most part. AA, AAA and CR123s are the standards in my kits. I have made an effort to use mostly AA battery powered items in most of my kits, but some devices that use CR123s cannot be replaced with AA powered units without making sacrifices.

The e+Lite does use coin batteries, but the size of that light and a spare battery more then makes up for the lack of "common" cells in the EDC relm. As for it being fragile light... I strongly disagree. I has held up to my beatings day in day our at work and in my off duty EDC fanny pack.