woods have different densities and textures, some woods absorb vibration while others resist it. same reason why when you mute its quieter and more muffled than playing open strings. i've got some old poplar lying around, and a first act with a #### body, i'm very tempted to start #### with them.
i think that a sick guitar design would be a center block of maple, ebony, oak, walnut, or some other really dense wood, w/poplar or some cheap wood glued to the sides, sawed into the shape, and hollowed out into a shell (not touching the block) then with a spruce veneer soundboard on the top and bottom, making sure that there is spruce to metal contact. result = loudness, hopefully balanced acoustic tone (probably trebly) but with a ####load of sustain, and no feedback which comes from soundboard mounted pickups (they would be mounted to the block).
