In reply to iamaclimber:
Burn time is generally good but I don't run it on full brightness all the time, mostly just for "where's the path going", running/biking downhill or night-O "where's the control" type of thing. Also I don't have another headtorch to compare it to I'm afraid.
The battery type will dictate in what manner and how quickly the light reduces when it is out of regulating mode. In my experience, NiMH rechargeables tend to "fall of a cliff" when near the end of their life with the voltage dropping quickly whereas alkalines tend to peter out more gradually.
The lower brightness spot beam is more than OK for fell running at night over flat terrain and the high brightness wide beam is perfect for walking/nav.
What's your intended use for the torch?
Tell you what, I'll try and remember to stick some fresh batteries in it tonight and time it for you