That's a pretty scary bunch of functions that an overzealous chord in the LH could accidently make happen... A STOP, for Pete's sake?

You could survive an accidental fill, but that?

Same problem as pressure, for those with strong playing techniques, IMO. Plus, of course, what happens if this is set up and then you WANT to play a strong note in the LH sound?!

You can't adjust the samples in a Roland arranger (their cross points are fixed) but yes, you can set up multiple vel-splits between the three UPR sounds and two lower... Or all five whole kbd sounds if they are layered as one...