I have both a P6 and an Ob6, and a seaboard Rise, so very interested.
So far i didn't have good results with the combo, due to the way aftertouch works on the roli, both aftertouch and velocity reacted quite strangely on the Ob6. Felt quite hard to control. Perhaps if i made a preset from scratch to use with the Rise.
Strangely, it worked like a charm on the Sub37, duophonic mode is awesome there with the Roli.