Does Guitar Fretboard Material Affect Sound? Is my question. Specifically I'm asking about electric guitars and maple vs. rosewood vs. ebony. And wood necks, not aluminum. Not asking about thick vs. thin frets, just the fretboard material. Thank you!
As pointed out in the comments, this is a contentious question (though not as bad as "tonewood" for the body of the guitar). Some people (in particular manufacturers and sellers of electric guitars) insist that of course there is a difference. Others point to the lack of reproducible tests with proper protocol that would show a difference.
Looking at it from a physical perspective: the amplified sound of an electric guitar is generated by the motion of the strings in the magnetic field of the pickups, which is then picked up by the PUs, filtered in the electronics and modified in various ways by the amplifier, cab etc. The movement of the wooden parts only play a role insofar as they absorb energy from the movement of the strings - i.e., any energy that is transmitted into the neck or body is, for all practical purposes, lost to the sound of the guitar. The two main points where energy can be transferred from the string into the wood are the bridge and the fret.
So in principle, if you had a fret that was anchored in a rubber-like material, it would probably absorb quite a bit of the vibrational energy, leading to faster decay and (depending on the frequency dependence of the absorption) probably a duller tone.
However, no one uses rubber for their fretboards. The commonly used woods are reasonably hard (for obvious reasons), and I would not expect a significant difference in sound - significant as in, you can reliably hear a difference, let alone one that cannot be compensated by a tweak of the tone pot.
I would also expect the size, material, and finish of the frets to make at least as much of a difference - after all, they are in direct contact with the strings - but you don't see a lot of marketing hype around "tone frets". Also, there are at least a dozen factors that have been shown to have a detectable influence on the sound of a guitar, so don't worry too much about the ones that seem to be more in the realm of speculation.