the 3 buttons are just the main customisation features arranged together.
Dynamic accompaniment was rather good, you had 2 half fills that were triggered by left hand pressure or right hand fast playing. These would sometimes spring up in the accompaniment just as you hammered at a climactic bit of the song. The effect while playing was much better than my attempt to describe it, and it really made the backing interesting since was used sparingly in addition to the normal fills, variations etc.
Again, there were a lot of complaints that nothing ever happened, what is it?, I can't hear it, etc so it was dropped I think just to save the same hassle on the next board.
I would like to see programmable, editable half fills like this available from composer with programmable velocity switch,and maybe right hand note speed detection, relative to tempo?