I've done some (unscientific) testing and the lithiums definitely last longer than alkalines with LED flashlights, but nothing like 3x or 4x longer which is how much more expensive the lithiums are over regular alkaline. So my curiosity would like to poll the GT trust to see who uses lithiums in their flashlights, who doesn't, and any compelling reasons/opinions why. I was about to buy some bulk batteries and I think I'm going to go exclusively lithiums from here on out..reason being, I've had one too many "explosions" of alkalines that sat too long in a flashlight, and I've even had alkaline batteries "explode" in an unopened pack that was only a few years old. Seems the dependability/shelf life of the lithiums is in itself worth the extra money, plus they last a little longer. What do you guys feed your AA and AAA flashlights?