I hear that. Here's what I take away:What does the OP mean by "Poly"?
or other 2 part cat finish?
The finish can indeed have an effect upon the guitar, but this is limited to the film thickness, assuming that we are talking about a hard finish that resides on top of the wood.
Other than that it is important to realize the plusses and minuses of any finish choice, as there are compromises involved with each.
Most guys mean, all of those. If they even know the difference, sometimes.
I like to call these "Catalyzed" finishes. And yet, some of today's "nitro" is not strictly just a drying finish. Chemical reactions have taken place there, that can't be undone with mostly harmless solvents.
Anyway, I am here to say I like a solvent based finish, because I can get better results when I polish it or repair it. And I like the feel of the "lacquer" finish. Less inanimate - more like the touch of human skin.
If there's a difference in tone, it is strictly through the back door. So to speak. I enjoy the experience of playing the nitro finish guitar more; and I maybe put a little more heart and soul into what I am playing. Even if the difference is small, it is maybe because I care a little bit more about what I am playing -- when I play lacquer.