I just been capturing 35 tapes of HDV over firewire into ProRes 422 (not HQ) on my G5 2 Ghz, 4 G Ram.
It works fine, been using both a JVC 720p and a Canon 1080i camera as decks. It has been captured onto a CalDigit VR 1,5TB, firewire 800 hard drive and then I have made a safety copy of the files on another drive as backup. It all plays back perfect, even 3 layers of pictures with superimposing, crossfades, text etc. the render times has gone down from my former HDV projects and the improvement in picture quality when I’m doing color corrections is great.
So what is all this fuss about not ProRes 422 not working on a G5?