I have used controller keyboard with modules several times, Ketron Midjay, Roland BK7m, Ketron SD40, and always find there is too much stuff to deal with--extra cables, power supplies, screens, etc.
I would really like to keep everything in one package, one keyboard.
I like my setup and adding another keyboard to the Korg would complicate that.
But to answer your question, yes I have thought of it.
I can use the PA4X o.k. still; but not sure how much longer. We'll see how the fingers and wrists hold up.
There are no bad choices, just some that fit better.