Installed this alternate iPad keyboard, http://shiverware.com/musixpro/
today. Started up Addictive Synth, Musix Pro and Cubasis. Set a new midi track to send and receive on virtual midi, got everrybody talking to each other (remember to set background audio everywhere) hit record and switched to the alternate keyboard.
It all works! Recorded the midi, played it back.
The hexagon kbd is a neat idea, all the harmonies are laid out next to each other. Plus it's on a Holiday special price.