Welcome Bob!
While they have come a long way in recent years, most run-flats still tend to give a very rough ride and don't offer the best grip that most 'spirited' MINI drivers desire. I ditched my runflats almost imediately. most will wait for them to wear out then go with something else.
As for the lack of a spare in the S models, 3 options:
1. keep a spare in the back seat (Chevy cobalt spares work on our MINIs)
2. carry a can of fix-a-flat
3. get AAA or another roadside assistance company and let them come fix it if something happens.
I personally do none of the above and just figure if I'm out of town, I'm usually with other MINIs, some of which have spares and would probably be nice enough to let me borrow.