I currently use the iOS app NAVICHORD to be able to create simple chord progressions which are simple 3-5 note chords played just straight.

NAVICHORD lets me feed the MIDI from this chord to one or more iOS or external synths and lets be assign the bottom Root ( or slash bass ) to a bass sound or arpeggiator while feeding the entire chord to - for example a synth with a pad preset, or a synth with an arpeggiator.

I use Ableton Link to synchronise the temporal BPM and bar-positions to every other app running in iOS ( or on a MAC/PC DAW )

Simply feeding this chord and its ROOT midi note to instruments in an iPad rig - wired by MIDI can produce some wonderfully rich multi-arpeggiated sounds - from simple chord progressions entered into NAVICHORD.

But navichord doesn't have the rich feature set or number of bars or arranger feature of iReal Pro.

iReal Pro would find a totally new user-base - one which even uses iReal Pro in LIVE situations for PLAYBACK instead of merely for sight reading charts - if iReal finally supports Ableton Link - and - instead of using its internal instruments - allows us to send MIDI from any style - to external instruments.

The sonic potential and scope for reinvention of old jazz standards with external Ableton-Link-syncronised drum machines would be so much fun.

And would turn iRealB from being just a practice tool and on-stage "RealBook" into an actual music performance and production tool.

ABLETON LINK + MIDI OUTPUT !!! MAKE IT SO!!!