what are you actually going to be recording?
Number of musicians is irrelevant.
What is important is how you are comforatable with a sequencer's workflow and interface.
(and go to a music store that has them and will let you play with them before buying if you can..)
If money is not a problem and you don't want to have cables everywhere or deal with patchbay's then get one of these.
http://www.yamahasynth.com/products/n8n12/index.html
I've had one for a week and just cannot get over the sound quality. The DAW integration is awesome. All kinds of routing options but it's easy to use!
I have the instruments and have been recording to garageband for a few months now, thought of upgrading a little since I'm going throught the line in jack on the Mac