Few things to consider:
-A good mini-DV camcorder will have much better low-light performance than a consumer HD camcorder. My old Sony TRV-900 produces a much better picture in low light than my Canon HV20.
-If you drop a camcorder chances are you will have a problem, regardless of the format.
-The SD9 is a pretty decent HD camcorder. Don't expect miracles unless your budget is over US$ 3500.00
-HD needs a much better lighting. One of the reason why many networks took a long time to broadcast shows in HD is because they had to rebuild studios to provide a stronger lighting.
I was so happy without HDR...