Originally Posted by CC 330i
Run flats are heavier by up to 10 pounds per tire (from what I have heard) so it stands to reason that less unsprung weight would make for a better ride.
According to Tire Rack's specs on the Bridgestone Pontenza RE050A in a 225/45R17 size, the run flat version is 27 lbs. and the regular version is 24 lbs. That's enough to make a small difference in handling, but I'm guessing the bigger factor is the sidewall stiffness.