We had RFTs on our MINI Cooper S go flat twice. The first time I took it to a local Firestone Tire dealer (these were Dunlops and Firestone is their distributor here). They replaced it free of charge no questions asked and even balanced the wheel for me.
The second time the tire was old enough that Firestone would not replace it. I plugged it with a $5 kit, drove it a few miles to heat it up, trimmed off the excess plug, and had the wheel/tire balanced again since the plug changes the weight distribution. That tire ran another 7,000 miles until I replaced the set. Mind you, it was a very clean puncture near the center of the tread; I wouldn't patch a runflat that was punctured near or on the shoulder. I should also mention that in my youth I plugged many punctured tires while working at a gas station so I am familiar with the procedure.
Runflats have gotten better over the years, but I'm still not a fan.