I’ve probably driven 250k miles in cars with run flat tyres (including some ‘spirited driving’) and have never found them to be awful – far from it. It’s not always convenient to have to change tyres as soon as you get home. I once had a 250 mile round trip commute, working very very long days and went through a spate of punctures. It was a godsend to be able to carry on using the car until it was convenient to get them changed.