on a mtb no idea,
on a road bike the hi-mod is the only reason I went to a supersix, otherwise I would have stayed on Caad 10/12 etc.... That is for stiffness reasons.
I have no idea on vibration dampening between the frames. road surfaces vary so much and i run so many different tires. plus it is too easy to acclimatize to whatever you are riding.
If you have the money, buy the hi-mod