Have either of you thought about using the keyboard's onboard Sound Creator program and editing the piano voice until it sounds the way you wish? It's really not at all difficult.
Cheers,
Gary

_________________________
PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)