I drive an '06 GS430. The original Dunlop run flats were replaced at 15,000 miles because three of the four would not hold air (the dealer remounted them several times which only made them leak air more quickly :cries: ). Yes they had a rough ride but that is a characteristic of the very stiff sidewalls that run flats must have that makes them run flats in the first place. I didn't particularly like the rough ride but I was OK with it.
But when I had to replace the Dunlops, I switched to Michelin Pilot Sport A/S, a non run flat tire, based in part to what other LOC posters have said about run flats in general. I am glad I did because the difference in the ride is like night and day. Very smooth, very quiet, and still have a lot of grip for spirited driving. And a bit less expensive too.