I have a Ketron foot controller and a Roland foot controller, neither of which will work on Korg or Yamaha. Yamaha's is too big and heavy. If I really get interested enough in PAX3, maybe I can swap somebody.
I can get by with the 3 inputs on Tyros, but I really like about four or five. You need sustain, vocal harmony, break, and text page for sure. More than five, and my size 13 feet can't find them without looking.
DonM