I think the only issue you are going to have with those Roland controllers is that they have a LOT of stuff on the left side, which is RIGHT where you are going to want to put the BK, in close where you can hit the Fill and Variation buttons, etc..

For the full arranger player, having the buttons close to where your chording hand is is pretty important. Look at the layout of most arrangers...

Me, I'd look for something with a nice empty area on the LH side where you can secure the BK to the keyboard (that heavy duty, all plastic Velcro does a bang up job of anchoring things like that very securely).