One the reasons I stay AA/Eneloop/14500 based is lots of back-up options.
I EDC a 2xAA iGo PowerXTender for my smartphone, so I can cannibalize those for my QuarkAAX. Have a AAA Revo back-up light on the keychain, and spare AAA in small organizer, along with a BIC lighter, Leatherman Squirt, and some cord. The AAAs can also be used in the Quark by rolling a couple dollar bills around it, and wadding some tin foil at the negative end, for spacers.
So all in I EDC 2xAA Eneloops, 1x14500, and 2xAAA Eneloops in three pockets (would be the same in shorts/T-shirt), I figure I could muster up about a 1000 hrs of light out of that if necessary...course, any convenience store has Alks too.. Ya think that's enough?