I feel that it would be a great learning tool. A guy used to work with me and had a synth/piano and he could always play in C. Meaning, he could set the synth/piano to D, A, F# or whatever but he could play the chords in C.

I always thought it would be nice (and this might be available) to have a synth, say you're playing in C, the synth would then block any notes that were not in the C scale (or whatever key). A person that was, say a guitar player with a fair knowledge of music, knows a few keys on piano, could fake a lot of stuff like that.

"The desire for fame is the last infirmity cast off even by the wise."
Cornelius Tacitus