Right now I have the Gen3 digital headlight. Works okay, though it does interfere with my HR monitor (Vetta S100). I minimize that by putting aluminum foil around the battery compartment - foil elsewhere doesn't seem to make much difference - but it is a hassle.
Anyway, supposedly it should last on high power for 6.5 hours, but that is, to say the least, a generous figure. Maybe the problem is with the rechargable batteries gradually becoming less efficient, but they are well under half (maybe not even a 4th) of the recharge cycles they can handle.
My longest rides (always starting at night) can easily last 4 hours and sometimes I have been out for 6 or a bit more.
I'd like a brighter light, but so far the only one I've seen that lasts long enough and probably with time to spare (for insurance) is the Niterider Moab - but that is a $500+ item!
Someone here also mentioned that HID light can tend to have more EMI issues than some other types so that is of some concern with my HR monitor issue too.
Anyway, I'd like to gather some suggestions with two things required:
1. It be brighter than the Gen3 digital.
2. It lasts at high power at a dependable 6 hours or more. Well, I'll adjust that - if it has multi power settings, it needs to last 6 hours or more at a level that gives more light than the Gen3.