When playing live I find I use a sustain pedal very little, but now that I keep it plugged in all the time I find I am using it more often - probably a good idea to have it there all the time.

I haven't used an expression pedal since i started playing an arranger because I found that I was using the pedal too much, ala organ. That works well for me now - no expression/volume pedal. But since I got my XK-1 I have bought a FC-5 (??) pedal and use it for the organ only. That is the only way to play organ - with your foot on the pedal. I want to experiment with using the expression pedal on the arranger, but haven't yet. Hope this makes sense.