I've tried to do gig photography a few times, and concluded that (1) you have to be really good at focusing in low light, and (2) you have to be really good at buying lots of film. Exposure seems like it's not that difficult, in the sense that stage light levels usually don't change too much, so it can be a "set and forget" thing. But usually the aperture will be wide, meaning minimal DOF to save you from focus errors; I've lost far more gig photos to focus problems than to exposure problems.
Normally I don't like autofocus, but this might be a situation where a *really* *good* autofocus mechanism would help. A bad one will just hunt endlessly in the low lighting, of course.