who cares if it has features you don't need, if it has features you do need (like good sound) Anyway, the dac is apparently much improved, plus it's USB and not firewire, so you actually could use it on the air.
The steinberg is a usb version of the MR816CSX
For $600 you definitely should get the duet 2. By all reports, it's fucking fantastic. Then you can report back here and let us know what you think. Or stretch the budget a bit and get a Steinberg UR824. Also, report back on that when you do, because that's on my "to purchase soon" list. After I quit investing in stupid synthesizer gear.
I'd personally use (actually I DO personally use) different wall colors to carve up open floor space. We have 3 wall colors (one of them green, in the kitchen) in our kitchen/living room.