So I got one of these recently, and just put it on a board. I'm quite impressed. I had the original MC6 at one point, but I didn't really like the screen. So the three screens for the MC6 Pro seemed really interesting to me.
All I've really done with it right now is setup the three bottom switches to change the channels on my Mark V, using the first relay output. I've customized the colour strips for them too, and put them in a toggle group, so that when I activate one of the bottom three switches, the other two have their strips go black so they look disabled, and the one I pressed goes either green, orange, or red, depending on which channel I select.
I've setup the bank so that on bank entry, it activates midi clock. Then I've got an external FS-5U switch connected to one of the omniports, and this sets the internal clock speed, which goes out via midi but also out via another omniport, which means I can sync the tempo of my Meris LVX and Boss DD-8. Eventually I'd be curious about getting the Boss DD-200 to replace the DD-8, but for now it works fine.
I've got three switches across the top of the MC6 Pro, that I'm thinking could activate three "scenes" on the board... so that's the next stage.