I've had good results with the Presonus interfaces. And, I have it from good authority that the MOTU interfaces are also quite good. USB & Firewire... none of the USB devices I've seen give you more than four inputs, simultaneously. I've seen, and used, Firewire devices with up to eight inputs, simultaneously. I've heard of some Firewire devices that provide up to sixteen inputs. So, the real difference between USB & Firewire is the number of inputs, and outputs, that can be used, at the same time.