Well, basically you're thinking the other way around......what's perhaps best is to look for a camera that has a lens that has a good enough F-number, like 1.8, 2.8 and so on and then you won't need any faster film than 800 at a dark concert. The shutterspeeds will become fast automatically, with or without shutter priority. On the other hand, if you go for shutter priority with a lens that's not bright enough (like 5.6 or even worse) you will underexpose the shots incredibly. In the same situation a 1.2 lens needs only half the light that a 1.4 lens needs for the same shutter speed with the same film. A 1.4 needs half of a 1.8, a 1.8 half of a 2.8 and so on. So it's best to look for a camera with as good as possible f-number, instead of just shutter priority - cause it would be a shame to waste your hard earned money :) Hope that helps a bit =)