I had a detailed look at this yesterday.
its an interesting idea... latency (and more importantly jitter) is a concern using a PI, as it doesn't seem to use a specialised realtime linux build.
this would actually be more interesting sitting on Bela (and could be adapted easily enough), but im not sure it adds much to Bela, since it already has supercollider running, and a cape for multiplexed analog I/O.
but perhaps bela couldl learn something from it.
Im going to follow it though, it will be interesting if users start sharing designs on it...
(I was a bit disappointed, they hadn't publish the schematics / SC code for the MITT )