Bachus, an sd9 doesn't tempt you as an (almost) all in one solution? I imagine you're somewhat used to 76 keys with the pa4x..
Well, to be honest, i mostly play on the kronos, and thats 88 key.. just a single button and it comtrolls the pa4x left and right.. or just the chords and use kronos sounds.. i only use the pa4x keys occasionally.
Over the last few years i developed a favour for weighted action...