I have a can of Holts Tyre weld. The way i see it the Tyre weld will get me home if the puncture is not too severe and if the puncture is too severe then i'll get the car recovered to home, get the tyre repaired or changed. The situation would not be much different if i had RFT's fitted as they assume that you are within driving distance of an 'open' tyre changing facility that has a RFT ready to fit (unlikely), and even if by some chance they did have a RFT of the right size and manufacture available i'd rather pay 10GBP for a repair or 80 GBP for a new Non RFT tyre instead of a definate NO repair for a RFT and a definate 180GBP for a new RFT to be fitted (and thats just the front tyres.)
All in all i think that None RFT's are the future.