Leo you are too modest, You have produced many multipads, every one a cracker. I've done some myself from scratch when I've needed to. I don't think you can change the timing or the groove, yes they are produced in real time , I think they can also be produced by step recording as they take the tempo from the song they are added to.
I will look at how to produce one on the Motif as an MP is only a one track midi with chord recognition and loop. The arpeggiator on the Motif should be useful.
Spike