Studies show that tone of an electric guitar is only affected by any material that is applied to a solid wood body over a 1/4 inch thick. This mostly applies to laminate tops such as carved maple tops and other wood laminates... Finish on an acoustic is essentially just for looks. I think most would be able to tell the difference between a thin finished Nitrocellulose finish of the old days and a thick poly lacquer finish of today though. The tonal qualties of the guitars would be the same... However the Nitro finish would be a shade louder.