Chris,
The Quattro will only function as a 2x2 I/O device when using the WDM drivers, and I'm not sure, but they (their WDM drivers), could even be limited to 16 bit operation only, in order to get more I/O from it you would need to use the ASIO drivers, and there are limitations under the ASIO drivers as well, recording at 44.1 or 48 khz you get..
4x4 I/O at 16 bit, and 4x2 or 2x4 at 24 bit
You could get something like Cakewalk HS2 and use it for tracking, then import the tracks into CEP/AA for editing/mixing, I'm not a fan of using usb for audio tho, I have
an Edirol UA-20 2x2 usb interface, and the performance of that thing sucks donkey balls, what a waste of money, the newer usb-2 interfaces are supposedly much better because of the increased bandwidth of usb-2.
Have you looked at this yet?
http://www.presonus.com/firebox.html
I'm using a MOTU 828mkII with a laptop as my main rig right now, but I'm thinking about getting one of these for a little more portability.