The 23d M Sport with it's sports suspension, 18" wheels and run flats handles very well, and in my opinion provides just the right amount of firmness (just avoid driving into potholes and slow down for speed humps!!!).
I'm considering changing to 19" wheels when the tires are due for replacement but am not sure if there will be any additional benefit other than asthetics.
Somewhere on here is a post with photographs of a Le Mans blue M Sport with 19" wheels and performance brakes etc and it looks amazing.
Mineral white M Sport now that's going to be special
