I have run flats on my 3 series and they are fine. The car corners like it’s on rails, it isn’t noisy and it’s definitely not uncomfortable. I wouldn’t do without them.
My positive experiences with run flats were on both 3 and 5 Series cars. I thought that BMW had pretty much done away with them, so I’m surprised to hear that you have them. Sadly, our X1 doesn’t have them.
They came with the larger wheels I upgraded to.