I've got Continental run flats on my 335xi ( 18,000 miles so far) , and find them to be no problem. They handle fine in the twisties,
and I don't find their firm ride at all offensive ( with 17" wheels). They are noisy however.
Having said that, I see no real advantage to run flats, especially considering that if they do puncture, many tire deales won't repair
them... so what's the point ?
Next time around, I'm switching to Michelin Sport A/S just because I like Michelin tires on my cars, trucks, and bikes. As already mentioned,
a can of stop leak, and a small air compressor like on the 987 should be sufficient for most situations. Saving a few bucks
vs runflats is also a plus.
This is based on my experience.... your results may vary

.... Tom
Wunderbar !!