I've video recorded a lot of live performances in my career. As important as video, in your case, is sound, so you'll want to be able to control the recording of the audio as well as the video. Since you're asking on the Canon Cameras forum, I'll suggest the XH-A1S. You'll have professional level video recording in both SD & HDV and professional control of your audio. You'll be able to take a direct feed from your main mixer. If you prefer, you can also get a hard drive recorder, such the one from Focus Enhancements, FS-CV100, for tapeless recording or simultaneous tape/tapeless recording. Check the B&H Photo website for pricing and availability. This all represents a fairly modest investment. Good luck.
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We could give a thousand recommendations, but it doesn't matter if it's not in your price range. The XH-A1s is certainly a great camera, but if you're budgeting, say, under a grand, your options will be along the lines of a well used Canon XL-1 or Panasonic DVX100 or a newer consumer cam like the Canon HV40.