Hi. We've been using cheap USB 3 bus powered drives for a 2 or 3 years now to transfer footage on shoots and then transcode or edit in fcp7 premier cc and even Resolve on mbp laptops. Never had any problems with 1 or 2 streams of proRes 422 or HQ and I'm pretty sure it's fine with 4444 as well. We also edit with native MXFs from the F5 FS7 and C300 without any problems. Haven't used FireWire for ages and it's really noticeable when we go back to our 2008 Mac Pro which is our main edit suite without usb3. We have an Ethernet based network storage setup using an old G5 Mac and can't see any difference in speed using that. We've probably gone through about 10 western digital my passport 2tb drives without any problems other than filling them up or them just dying through lots of usage. Hope that helps.