Maybe the hardest part of giving up 'perceived' control of an instrument is letting go of control by hand strength.

I didn't start out on piano, so I don't associate dynamics with control by hand. That's not true of stringed instruments for me. It's still difficult for me to play electric guitar because my brain tells me that volume and dynamics are controlled by my hand strength.

However, with my S970 and Tyros, it only seems natural to control volume/dynamics by controlling a volume knob.