USB 3 will be a massive plus for digital audio. Massive bandwidth and - based on early reports - sysytem latency almost on par with PCI-E and host-cpu load-impact so close zero it wont matter - all of this is due to the new usb-protocols introduced for USB 3 ........
however ....... I would avoid it like the plague until it is put nativley inside the chipset by Intel at the base-silicon level - this is due in the next 3 - 6 months.
All current USB3 solutions are "chipset-bolt-on" solutions to the motherboard -
none of them are Intel-chipset-integrated at the silicon level - good news is though that the native Intel USB3 solutions are almost here.
Tim