I have this one by a German company that says it is safe for tire pressure monitors. I used it for my 335d sport when switching to non-runflat Michelin PSS's but haven't tried it for a flat yet. I also carry a flat repair kit that I have never had to use.
Most of my flats occur around the home base so I can often just remove the tire in the garage and bring it to the tire shop.
For $150 I would order the kit from BMW if I was able to. I'm on the fence on whether to use RFT's or not since one time I did drive about 120 miles on a bad blowout that ended up ruining the wheel also (I know, they are for 50 miles or less). This brings me to think that only a spare tire kit would work should I need to drive long distances away from "civilization."
PL