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 StoreAudiobus is the app that makes the rest of your setup better.
Different Gadget
Just a quick romp with Different Drummer driving Gadget. I'm starting to like the workflow with this combo. Probably shoulda dialed some of the tracks back a bit, and the lead glitches a bit, but I think that was a combination of the DD sequence and the glide used in Chicago.
I am wondering if you can set Gadget tracks beyond 16 measures. I'm sure I saw comments on this, but I don't recall the answer.