The XP-C is the smallest of the XP family, behind the larger XP-E and much larger XP-G. I'm not sure when it was first released, but its not very good on most fronts--its rated current maximum is .5A, and highest bin is Q5 (which is about 20% dimmer than the highest XP-E at comparable drive current, and even further behind an R5 or S2 XP-G). (The one advantage is that, when overdriven, it has crazy surface brightness and, consequently, throw. See the DEFT-EDC for an example).
Judging from the battery configuration and single mode, I'm guessing that the light is direct-drive. Coupled with the slightly higher Vf of the XP-C relative to the other XP models (to say nothing of the sub-3V-XM-Ls), this light will have slightly lower runtime than many lights with larger/more expensive emitter, but runtimes will be more dependent on the batteries you choose, since internal resistance comes into play with direct drive.
If its a linear reg driver, then all runtimes will be identical, as Vf does not come into play. Doesn't matter how bright it is.
