I tried the lights with 2500mah Nimh batteries last night and they seemed brighter and there was no red low battery indicator lit on the back of the light. I'm still not sure they are going to be good enough to ride unfamiliar trails for 8 to 10 hours through the night.

I'm going to try the helmet mount option to see if that helps but I'm definately going to need a second lamp on the bars too if that's the way to go.