The Pa3 would make a great keyboard for a new Korg user, or one with a PA500, or a PA1X...Not really for PA2x owners I don't think..
Got to lay out too much cash. The going second hand price for a PA2x (76) in Oz at the moment is from $2400 to $2800 (and they have to be in excellent condition as well)...So with those prices PA2x owners will need to stump up some serious $'s
For me, the Kronos + Roland MK7 module, or the MO XS/XF + Roland Module, or even the Groove XR + vArranger software and a 76 piano are looking more attractive, AND much cheaper

Dennis