It would be a killer feature if QC were able to record audio signals to an external USB HDD. This will allow for instant recording of ideas / loops, whatever comes to your mind
Not possible without a hardware change. QC is not a USB host.
From what I know (but I could be wrong since I am not a electronic engineer), the only difference (referring to now, not years ago) is a different software configuration and maybe that the usb port will not be able to drive current on the device.