I feel that changing the material of the bridge pin will change the sound only if it is a greater/lesser mass. A similar sound could probably be achieved by bolting the bridge onto the soundboard. I once had a 1958 J-50 with an adjustable bridge with metal bolts. When I had the adjustable saddle replaced with a bone saddle, the tone was much more to my liking. Somehow I feel this was due to reducing the mass of the bridge. I think putting clamps on the headstock (tuners and capos) could also change the sound of the guitar. If not, it certainly looks junky.