Don, you might want to consider the undesireable side-effects of rollbars--they tend to amplify bumps which hit just one wheel. On speed bumps (hitting the both wheels at the same time), rollbars could be 2" in diameter and you wouldn't be able to tell, but when one wheel hits a hole--WHAM!
Now I don't know how extreme the S bar change would be (I suspect very little), but if you can feel it helping noticeably in the turns you will also feel an increased harshness as well.
I say this because I also chickened out of 030/18" wheels because of potholes in the area.
By the way, Tweeks sells the rollbars if you want to check them out...