Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.Download on the App Store
Audiobus is the app that makes the rest of your setup better.
New Roland MV-1 and Zenbeats integration
So the MV-1 is promising zenbeats integration in Feb. It'll be interesting to see if this is more than just simple level control or the like, but interesting nonetheless. (Roland being Roland, I'm not particularly optimistic, of course).
Given the ubiquity of iOS devices, I'm honestly surprised that hardware manufacturers haven't broadly opted to offload/supplement features (full screen editing, e.g.) with phones/tablets ala the OP-Z. What am I missing here?