Great topic. So many victims (owners) just nod their heads and go along with the TPMS rebuild" (and the "Nitrogen Fill") because they know no better. Shops 'recommend' this stuff BECAUSE IT MAKES THEM MONEY!!! With tirerack being the 500 pound gorilla in the market, they try everything they can to make up the $$ elsewhere.
Sensors are usually fine, and in fact of they leak or fail, BMW can replace them! (Until my warranty is up.)
Keep it as simple as possible...but no simpler.