Hi Caleb,
Capturing your HDV material with ProRes won’t automatically give you superior [i]image[/i] quality; the key is that ProRes RETAINS greater image quality after several renders and the application of video filters e.t.c. as opposed to other codecs. But, the main reason ProRes is so great to use when working with HDV content is that it is far better suited to the editing process then the native HDV codec – using ProRes will reduce your render times when adding filters e.t.c. and I’ve also noticed that it really cuts compression times when you’re compressing your final cut for SD DVD. ProRes is generally better to work with if you’re doing any kind of extensive colour grading, too – in my experience.
The big drawback is that the ProRes format produces very large files (about 60GB per hour of HDV). I don’t know what capacity your scratch disk has – but keep that in mind. As for working with ProRes over a USB connection – personally I would be quite dubious about that. There is a good discussion about this here; https://forums.creativecow.net/thread/8/1000834. The other “solution” would be to capture the files to your macintosh HD during the capture and then transfer them to a FireWire drive afterwards before you start editing. Again – this is not ideal and I know many people would shoot me for even suggesting it! But if your options are limited…
It really boils down to; is this project going to require many video filters/visual effects? If so, ProRes will save you a great deal of time that will otherwise be wasted rendering HDV files and it [i]does[/i] seem to just work more harmoniously with Final Cut (I used to edit with HDV but would never do so now).
Best,
Adam