No, not really. Firewire 400 is generally a little faster than USB2, despite USB2's faster theoretical maximum speed (480 mbps vs. 400), but both are far faster than the rates needed to support audio. Firewire 400 is preferred for video editing work, because the protocol guarantees that the transfer rate will never drop below what is needed to handle the dv (digital video) format without dropouts, while USB's transfer rate will fluctuate and occasionally drop below that minimum. But for audio either should be fine.
Regards,
-- Al
Regards,
-- Al