I'd punch you in the face Milli if you weren't a girl. I'm always about to blow when my parents curb the wheels or bumper. :evil:
Patch, I'm not as familiar as my dad about tires, but runflats are much harder than standard tires so the bang when you drive over potholes is bigger. Normal tires would absorb them better and they also have better grip. I have no idea how are F10/11's but I have read on several BMW forums that especially 1er's (E8x) and 3er's (E9x) are said to be underdamped and they are crashy even without RFT's thanks to bad dampers etc. Those, who bought for example Koni dampers, BMWP springs and few E92M parts, report their cars drive much better.
I wouldn't care that much about wheels, OEM's are strong (they aren't forged, though) and we haven't had any issues with ours.
BTW, nice avatar mate.
Edit: Or you can sell the 20's and get some nice lightweight 19's on normal tires.