Good call SteveO.
that rubber piece looks fairly insignificant when compared to the amount of rubber, and damping, created from a rear hub cush drive setup. i'm sure this clutch rubber helps a bunch, they wouldn't put it in there if it didn't. though i'm feeling like if 30% of the bike's time (or more) is spent on pavement it would probably be wise to invest in a cush hub. more research...