It would be really helpful if you could use the iPad's/iPhone's internal microphone as an audio source alongside the Audio Interface's inputs. I would pseronally use it to route the internal mic's signal to my in-ear monitor. This way, I can hear my band members and the audience, as well as the feedback of my fingers hitting the keys and pads.

In order to loop cleanly with microphones, in-ears/headphones are the way to go. The downside is, that I sometimes feel quite isolated without the sound of your instruments and your surroundings in the mix. By adding roomsense, you could improve the looping experience a lot!