The mounting of the rectifier was changed in 2014. I haven't heard of any M3W having rectifier problems since. My own 2015 M3W has done 6500km's without a single issue. Why would you swap out a part that is perfectly serviceable?
I've had one of the MMC stock rectifiers fail after about 10,000 miles, mounted from new in the new position by the factory. My guess is that the newer mounting improves things a bit by reducing the amplitude of the vibration but that the real issue is the appallingly poor quality of the wires and their insulation leads inevitably to them fretting through and producing short circuits that lead to the final failure of the entire unit, with or without taking out the battery and ECU along the way!
