I have the same setup and I agree for the most part. Sport Suspension + 17's are the way to go.

 

Coming from a Z4 Coupe with 19 in Performance runflat summer tires and the sports suspension, my CMS All4 ride is like a pillow in comparison.... Still, I have noticed some pretty audible, annoying ride noise on certain roads. I will most likely switch to non-runflats and spend some extra money buying a compatible donut spare which I will keep in the boot or behind one of the front seats. I have no wife or kids so It's usually just me and the dog. I liek the idea of having the runflats, but I think I would prefer a smoother, quieter ride.

 

I have run flats on my CMS4, 18" wheels. Only had it four months now and am about to turn 10k, but I like the ride. Have taken my car on three long trips to date, Orlando to Savanna, Orlando to Atlanta and Orlando to Maine.

I plan on keeping RF tires on it as I like the safety feature. I do plan to switch from the Bridgestones that came on it to Continentals when the time comes. My GFs car is a '12 convertible and she just replaced her original RFs at 25k miles. Replaced with Continental Conti Sport SSR and they are better than the original Bridgestones. They are noticably quieter and give a better ride.

 

I had the run flats on my 2012 MINI Roadster, the ride was so rough it was painful. The ride in my new 2013 Countryman on run flats is like floating on air, in comparison.

 

I got a nail in my runflats this week. For me it was more stressful than changing a tire. I had a pump in my car so I could put some air in it and drive around without worrying too much about damaging the tire. As is well documented, local tire places won't repair them so I got a patch kit and fixed it myself.

I'm now certain that I won't get runflats when my OEM tires wear out. I'll keep a Slime Spair in my boot and call it good. It should get me going with most anything short of sidewall damage. That beats the heck out of a more expensive harsh-riding tire that I have to repair myself.

 

Before my Minis I drove all BMWs with run flat tires. They weren't bad. I guess because the cars were bigger. My first 2 Minis came with run flats and I kept them. On my roadster I switched from run flats 2 weeks ago and I can't believe the difference. The ride is comfortable. I'm not constantly swerving to avoid bumps in the road. I will never drive on run flats again. I purchased the mobility kit and a tire plug kit..... Just in case.

 

What's the mobility kit??

 

I don't know what the big deal is. Seems fine to me with my run flats.

 

I was somewhat surprised at the ride quality with the Pirelli run flats on my CM but its still early days of ownership for me...

 

I just took my RF's off at 26k. They had approx. 5/32" left of tread . With them on I felt every little bump, crack & stone on the road. With NON RF's and of course being new the car is quieter than when new, rides better than when new and with the Strut Bar and torque arm inserts I think it handles better than new.