reasons to choose the Midjay Pro would be ...
.. a more compact and way lighter unit
.. more modern styles
.. don't care about creating styles (AUDYA 4 allows for this)
.. want more PLAYER features and less ARRANGER features (reverse n AUDYA 4)
.. large true color touch screen
... menu driven (due to less buttons to access functions)
... then Midjay PRO should be your choise