I just recently bought a GS460. With run-flats having a reputation for repair problems, high cost, quickly wearing out, and rough ride, I asked my dealer to swap out the Dunlops for regular Michlein P/S tires on the same rims. He even threw in the doughnut spare. I'm very happy with the results. It's probably too late to ask your dealer to swap yours, but maybe you could find a buyer for your run-flats and bite the bullet for the extra cost of a new set of regulars, knowing you probably have saved money in the long run -- plus get a smoother ride, fewer flats, and a longer lasting tire.
In my opinion, run-flats are not yet ready for prime-time. The technology is not quite there yet. They've been pushed onto consumers my manufacturers attempting to save weight, space, and improve average gas mileage (by removing the spare) to meet government mandates -- while trying to convince consumers that they should feel more secure, but failing to point out the negative factors. Actually the idea of driving 50 miles on a tire that will probably get destroyed and not being able to find a shop with the equipment to repair or replace it doesn't make me feel any more secure.