I have a focusrite Scarlet 18i6 coming in a few days (it's under the tree now) that gives me both MIDI and multiple audio interfaces, and am eager to see how it works with Loopy. It's definitely supported by Auria to bring in 18 simultaneous tracks, so it'll be interesting to see how Loopy supports it.
I just realized how necro this is, so apologies, but I'll post back when I know whether it works or not. Maybe in a fresh thread :]
Hey Raketemensch - did you ever get the Scarlet 18i6? I'm thinking about getting it if you've used it successfully with Loopy. Let me know.