Good question. I'm thinking that making a stress free fitment laden could be the better bet, but with good ISOs, a head steady that greatly limits port and starboard upper engine movement and employing the Mk3 head pre-loading spring may even the field; can't say. The down side is that anything that limits the drive line's movement would also increase the level of felt vibration to the rider; handling should benefit, but I would think each rider would have their own sense of where the balance of felt vibration and handling should be.
The rubber silencer mounts won't live forever, but, as mentioned by other posters in this thread, quality of the part and good fitment will go a long way to extending useful duty.
Best.
