i just put a 9oz nichols on my S4R (thanks chris!). this weekend was my first outing with it.
having twisted the throttle, but never ridden, a 620 with a lightened flywheel (felt like 0oz response), and hearing numerous stories about how twitchy they can be.. gotta have good throttle control.. watch out for bumps in the road, etc, i was nearly nervous. phooey. took me 5 minutes to get used to it and i LOVE it. much recommended.
we (aka, they) had a hard time getting the bike tuned to not run a little rough <3K rpm.
1) it's fine enough
2) i barely spend any time in that rev range
3) the 14t front makes up enough of what i need to deal with parking lots
4) the s4r has always been bitchy when it's cold or you try to ride it super slow
5) who cares! it runs phenomenal where it counts.