As long as the two (+-) switches are easily accessible on the panel, and not in some sub-menu or another page on a touch screen, I can't see a problem, although I do like on my Yamaha how the instrument waits till you hit a new chord before it does the change, rather than instantaneous.
One has to think of Irving Berlin, who, over his entire life, could only play in one key, F sharp, essentially only black keys.
He had a device attached to his piano that would allow him to transpose other keys to his favored one.
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.