I am strongly in the carry a spare side of the argument, regardless of the frequency of punctures there is to me the same potential risk as the current hard shoulder 'debate' on motorways.
Having had experienced a split tyre on the wonderful A9 at least a wheel change reduced the exposure to danger rather than the now necessary wait in a totally exposed location for help!!
But one other note - I was trying out lifting my new Crosstar using 'standard' scissor jacks, one had a nearly flat top (Honda)and the other (Draper) had a location groove for the re-inforced lifting points. The rear lifting points are thicker than the front so the grooved jack would not accomodate the lifting point.