I too had this disdain for USB as a media drive. Depending on your needs, it might be a good choice.
For a feature I had to edit on the field at DV-PAL resolution. I had rushes of about 10 hours and an edited timeline of about 2 hrs+. Sound was dual-system, so it came off BWF files.
I did the entire edit over a few months on my MBP connected to a bus-powered WD Passport drive (250 Gb) connected via USB. I could even have an end-to end presentation of the final edit off this single drive. And all the rushes were captured to this very same drive off a DV deck connected over Firewire.
Like I mentioned, all this was DV-PAL. If your needs are ProRes, or ProRes at HD res., then USB may have a problem delivering it cleanly.
If you want to consider GigE then consider iSCSI or AoE.
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Neil Sadwelkar
neilsadwelkar.blogspot.com
twitter: fcpguru
FCP Editor, Edit systems consultant
Mumbai India