Very true... the first car I had with run flats was a C5 Corvette. The tires were stiff, and because of the compounds used it went from decent traction to 'oh shit' at the flip of a switch. I changed over to regular tires and never carried a spare... but kept a small compressor in the back with a plug kit just in case. I sold that car with just over 200k miles on it... and I never needed to use the plug kit. Perhaps I was lucky... but I wouldn't bother with a spare at this point and I'd do like you did with roadside assistance.
Mark