Considering...
A) our streets are usually in much worse shape (pysical condition)than the typical track
B) most of us do not pay much attention to the speed limit (at least not 100% of the time)
than we can assume that A+B = C
C) We will be going fast on crappy roads
Maybe not quite at track pace and lean angles, BUT with this in mind a damper on the street is not so far fetched.
There are other things to consider too, geomerty, suspension, tires etc etc etc.
Most guys I know treat their favorite twisty sections like their own personl track (within reason

) so... you do the math. Most people who try them (I mean on the street) agree it's beneficial.
I would like to hear if there's someone on the board who's tried one on the street (fot more than 5 minsutes) and didn't like it? It's one of those thing you can't really comment on till ya have firsthand experince IMO.
If you've never experienced a bad headshake in your street riding, than it's a safe assumption that you riding style doesn't require one. That's my take, your's may differ

.
Personally I don;t see any negatives. Even if you don;t think it's required, it's not goign to do any harm. I will say this...probably any of the other 600's (expect the honda) would need one before the 6R. I'm talking pre 03 bikes, I have no exp with the 03's.