The Sony HDR-TG3 may be slightly out of your price range, but is still worth looking at. Tapeless high-definition, very small and portable, picture quality from what I have seen is comparable to HV20 / HV30 even in low-light situations which is, presumably, the kind of scenario you'll be shooting in (by way of anecdote, I know one person who has ditched his HV20 in favour of the TG3 simply because it is easier to get around with and still shoots very good video). The downside is that you have to use (expensive) Sony Memorysticks, but if you back-up your footage regularly, you won't need a whole bunch of 'em.
Bear in mind that the lack of light most musical performances occur in is beyond the ken of most (I'm tempted to say "all" but that's just inviting a flaming from the Canon HV fans) camcorders at this level.
My advice would be to forget about standard definition miniDV. If you're going to faff about with tapes, you might as well record high definition video on them.
As for audio, a mic input is great, but the mic is most likely to be mounted on the camera. For a music performance you'd be better off recording the audio independently and putting sounds and pictures back together in iMovie or whatever. If you can be bothered, that is.
Andrew.
