The concept of the RFT is excellent, If you are unfortunate enough to suffer a puncture you just drive on until you get to a repair garage. The memories of having to stop wherever you get a puncture and having to change a wheel is not something I cherish. My wife would'nt know where to start changing a puctured wheel with the spare. Then there are the safety implications of anyone changing a wheel at the side of the road, it's just not safe.
The somewhat harsher ride and the slightly more expensive cost of these tyres is for me at least a small price to pay for an otherwise positive innovation.