Nevermind… Got it figured out.
For other peeps with problems: be sure to watch info on http://www.jamorigin.com/docs/midi-guitar-for-ios/
Info about how to get midi output working and more is available there too!
NOTE: on iOS you better restart the MG app after an iap purchase. Under circumstances the nagscreen can popup unjustified, after restart of the app it should work fine.