Pertty much anything you do to improve road-holding will have a negative effect on the ride quality. That's not completely universal, but there aren't a whole ton of exceptions. The thing is, different people have different levels of discomfort they can tolerate and different levels of grip that they want to attain.
I am finding that, as I get older, I want the car to be more civilized on the street and am willing to give up a little bit of grip to do that. I'm still keeping the 140s and the 19mm sway bar (considering going to a 21mm one--crap, Br@d was right again!!) but I think I will change over to 60- or 65-series tires for street use soon.
The "sticky" tires will still be 50-series, though!
--DD