It does have full BMWSH and will continue to have
BMW can change the engine oil and do inspections that it, thats about £300 and they stamp the service book
And when the maintenance schedule says "Replace spark plugs"? Are you going to let BMW just replace them again or are you going to say "I did them myself, just stam my book".
You are aware that the E60 M5 has condition based servicing yeah? It doesn't go Ins 1, Oil, Ins 2, Oil, Ins 1 etc like BMWs of old.