I've tried to standardize my lights. What I wound up with is less standardization than I thought I had:

Surefire G2 (123 cells)
Mini Mag w/Nite Ize LED (AA cells)
Inova X1 (AA cell)
Petzl Tikka Plus (AAA cells)
3D Cell Mag Lite (D cells)
Photon Lights (button cells)

Between regular alkalines, rechargeable NiMH, and lithiums, by far I have lots of AA cells. Fewer AAA cells, even fewer 123 cells, and no spares for D cells or button cells at this time. (Shame on me; I need to change that.)

In a way, having flashlights that are powered differently boosts your odds of having at least something to use in an emergency. On the other hand, the various types of batteries are just one more thing to stock up on and tougher to rotate stock.

That HDS "EDC Ultimate" sure looks pretty sweet... <img src="/images/graemlins/shocked.gif" alt="" />