Let's look at guitars for a moment.
So, it is only really the electronics which make a difference?
Right . . .
Take an SG and a LP. As far as I'm aware, the pickup positions are the same in both. Now wire them identically, with identical pickups in each guitar & use the same type & brand of strings. And then compare them through one amp using an A/B box.
Electronically, they are the same. The pickups are in the sam relative positions. When it boils down to it, the only real difference is the wood in this instance, yes?
They won't sound anywhere near the same.
*As someone currently working on a PhD in physics*
Interesting thought; perhaps it's the amount and weight of the wood more so than the type of wood that supports your illustration.
The idea of multiple laminations reducing sustain makes sense.
I was part of an R&D effort years ago that studied building materials and sound attenuation. Multiply layers of plywood, especially with the grain crossed, offered comb filtering and I would think that the glue joints could not promote anything other than deadening sound transmission.
IMO wood densities and perhaps moisture content could effect sustain although I have nothing to prove this with.
Still believe that tone is MOST deteremined by the amp and player followed by the strings and pups; wood type and bolt on is insignificant in the equation IMO