Oh man, let's not turn this into another Audi vs. world thread.
That being said, in this day and age it is only a matter of time before BMW, Ford, etc get pwned by warranty claims. Yeah back in the day you could engineer a turbo to last forever; because it was oversized, laggy, and understressed. Now people won't stand for that- they want smaller, faster responding, higher-performance turbos... and they're gonna die sooner than a supercharger will in the same application.