And just to throw another monkey in the wrench, I've been looking at the JVC 100U. It's $5500, which is a bit more than the DVX and the XL2, but it's HD with 24pa and 720p. And the overall features on this thing, including interchangeable lenses, focus assist, etc, are utterly amazing.
It's taken me a while to be sold on HDV, but I've been very impressed with how it holds up in editing and color correction.
Just something more to consider. It could be that it's out of your price range, but if you're considering an XL2, then you should definitely take a look at the JVC.