Eugene, yeah, flashlight people call alkalines "alkaleaks" and advise against them. I haven't had leak probs so far with eneloops or lithiums. Eneloops in particular (that specific brand, not that type of cell in general) seem to have very good charge retention, like 5+ years. So they're almost always preferable to alkaleaks in those formats, with lithium primaries available for some special purposes (super light, cold weather etc).

Chaosmagnet, that is interesting about the Prism. I'll take a look for it, but I've sort of changed ideas. I figure I almost always have a 1aaa light in my pocket so it might as well be a right angle one, and then I could just stash a tiny headband for it. I resisted ordering a Manker yesterday as it had too many annoyances.

Hikerman, yeah, I think flashlight electronics (batteries, leds, voltage converters, MCU's) are now all quite mature and further improvements to them (short of some totally new technology) will be small tweaks. But there is still lots of space for new flashlight design in terms of things like form factors, as we are seeing here. I remember zinc-carbon batteries and they still exist, but are rarely seen these days, heh. Btw if you want a super heavy duty, super expensive headlamp, look up Scurion. I've never seen one but apparently high end cavers like to use them. I'll stick with Zebralight .