The Hi-8 camcorder will be better than the JVCs by a gnats whisker – assuming your JVCs have the usual lenses?
The only snag I can see is the recording medium. I think you’re proposing recording on the hard drive of the DVD recorder? Be very careful as you may have issues with compression – DVDs and DVD hard drives need to compress the data to get sensible running times. This does limit what you can do afterwards. If the idea is to live switch 3 cameras (not easy on an mx-30) and then give the finished product to the client without furter editing, I guess that’s ok.
The JVC cameras, via y/c to the mixer, and then to the recorder will subjectively give a very good picture – assuming the light levels are reasonably high. Mixing with Sony and JVC is always a little tricky due to the different type of picture.
I do this kind of thing all the time – the biggest expense is the camera ops – you really need them, very important for dance. From time to time, I’ll use a static unmanned camera at the rear of the auditorium, but real people and comms I couldn’t do without. They need to be good as you’ll need to adjust exposure manually – dance shows being universally moody lighting prone!
