Don, Have you ever tried tucking a reeeeeealy narrow controller under the PA4x? It'd hardly be noticeable, both sets of keys would be really close - there's no extra audio wires, or pedals needed - just a single midi cable. Sustain, breaks etc - all controlled by the 4x. The Korg might even power the controller via usb. As much as you use your left hand for bends, and such - this would give you the same basic hand position. You'd also have a full keyboard to play intros and endings on, or just to noodle 'round before you pick a song. You wouldn't even have to write, or edit a single Performance (registration). It's food for thought.