Consider the evolution of stereo speakers. The cones used to be of
paper. Now they use high rubber, very stiff alloys for frames _and_
cones, liquid cooled coils, graphic equalizers, and all sorts of new
technology and materials.
A homogeneous material like a cross grained carbon fiber material of the
proper thickness at center and rim, crowned and ribbed to support the
strings and allow flexibility, with proper loading and other things I
don't know about, could make one hell of a piano. The velocity of sound
and its dispersion throughout the material are more likely important
than the material itself.
Just some things to think on.
Newton
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