brightnorm,
I've run that combo for about fifteen minutes about two weeks ago. Had a mountain lion roaming our neighborhood and me and a neighbor went out to try to follow it for animal control. He had a 6D maglite (or something that looks like a baseball bat) and his .357 and I had the C3. He was totally wowed by the output as it made his maglite look pitiful. He kept commenting on how small and extremely bright it was. Oh, getting off topic. I guesstimate it was fifteen minutes and it had a more runtime to go. It was not even yellowing, though the whole light did get extremely warm. When I got home, I measured the voltage and it was 3.87V per cell. I thought, cool, I probably have another ten minutes of good bright light.
Li-Ions are the way to go if you have the proper charger. I don't worry about overdischarge too much since I always top off (good for this chemistry) and if the light starts to yellow, I quit using it. I have been looking for a SRTH/N2. I'm really bummmed they're no longer made. That would make my C3 a nice little light saber. BTW, that was one situation where a LED light would not have done the job (even a 5W) The throw of an incandescent just can't be beat.
CM