i did a fair bit of research into this when i renewed my warranty last year, and in the end i swallowed my pride and went back to BMW.
It's really worth it, and you don't even need to continue using BMW servicing any more to keep it 'intact'..
go on their website and up the excess, take off breakdown cover etc etc.. mine was £45 a month in the end. never claimed though
Now: F21 118d M Sport
Gone: E92 325d M Sport