I would recommend using a firewire interface rather than USB. While USB 2 is technically faster than fw400, it operates in a burst mode that is not ideal for audio transmission.
You'll be able to achieve higher track counts and probably a higher degree of reliability with firewire.
Disagreed.
I am both an Edirol dealer, so have had plenty of opportunity to play with USB and Fire-Wire interfaces and run various multi-track recording set-ups.
USB 2.0 has never cause me or customers any issues. USB2/Firewire, in practice, makes no difference that I have been able to see.
USB 2.0 is more than fast enough to handle 12 tracks of 44.1, 24 bit audio, without a glitch.
The attitude you are expressing is (AFAIKS) a halo effect from the days of USB 1.0 and early drivers for this type of gear (which
were a bit crap). USB 2.0 is mature, fast and stable and most/all? manufacturers seem to have got their act together on the drivers.
Today I would recommend people buy USB 2.0 as it's ubiquitous while fire-wire ports are becoming rarer.
digifish