For those of you who've missed it: The UFX just went class compliant, so now one can record 22 tracks to the Ipad. I've only recorded single tracks so far, but no real issues. I had to use mode 2 for Sampletank though for a slightly higher latency than I'd want. Matthias also hints "And there is more to come!", which is not yet disclosed. I kind of figure they want to make a proper mixer application for the Ipad, but that's just a guess.
RME User Forum / Fireface UFX goes Class Compliant!
One thing that's a bit annoying is the latency of direct monitoring in Auria and other recording apps (Cubasis). I'd prefer a simple way of accessing the built in UFX mixer. You can save mixer configurations and load them up in CC mode though, which kinda helps.
Another issue might be that it always records with FX applied. In MacOS and Windows, you can choose whether the interface records the channels wet or dry. Of course, one could always use DUREC for this.
I didn't try the MIDI ports, as my simple midi controller only has USB, but I managed to get it working over Wifi (USB controller -> Windows 8 -> Rtpmidi -> Ipad).
The CC mode is a nice bonus feature indeed and soft synths like Sampletank, Animoog and others on the Ipad have never sounded better.