My university has a firewire 410 (lets call it the little brother to the 1814) and it works well. I do have some issues with the M Audio drivers. The school is still running 10.2.8 on its machines (a PM G5 and a Al PB G4) and occasionally the M Audio software will mute all outputs. This is really annoying, especally when trying to do a in-class demonstration, and no sound comes out. Basically after about 10 mins of troubleshooting i found the problem, and now am aware of it. Note: it does not happen everytime, and it actually seems to be totally random as to when the software for the 410 mutes outputs.
Other than this occasional problem i love the 410. It is solid, fairly user-friendly, and the price is not that bad. So check out the 1814, or maybe look at rack mount unit such as the PreSonus Firepod (also comes bundled with a copy of a low-end Cubase (SE??..cant remember))
i would also only think of going firewire for your needs. USB, ehhh. I have plenty of USB devices that use my ports on my PB, and on the schools machines as well. The firewire is hardly ever touched, so that leaves a open firewire port for audio devices and it seems to be faster and more stable than USB hardware devices.
-cameron