Bachus,
I used a CME 76 key MIDI controller.
If you are careful and brave...you can use the Tx or PA2 or whatever rght on it (on the front) then you have to support the rear. I use a on-stage stands 2 tier unit and have modified it to hold the arranger at the rear. The way I had it last time I did this is not secure enough for gigging. You could easily make it more secure.
I used the split on the CME....left for arranger LH...right for any other voice you want. R1,2,3 on te Tx or PA2.
I also had my Kurz MIDIed up so I coud use right split to plat sounds from it...simple enough.

Actually with a Tx I would use a 61 key cotroller and build a base for it unless you use it for gigging...then I would do what I already said but better.

I had some issues with this setup. IF I remember correctly on the T2..LH hold didn't work right...on the PA2 I think the lower worked OK with LH hold..but there was something else that sucked. I would have to set it up again to see the details.

I also had the Roland PK5 pedals in this setup.

I may go back to it. I just moved and can't find half my **** , so it will be a while.

If I went T4 I would absolutely do this...If I go with the new Korg...depends, If I get a 61 then yes...If I get a 76 nope...not needed.

The MIDI setup is trivial.

Lee S.