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.