If you don't like your bike getting dirty, stay at home and watch TV.
I think this thread highlights the differnce between roadie thinking and MTB'ers thinking. The OP claimed to have a road background, this best bike thing may even make sense on the road, I'm not sure? Mountain bikes get muddy and f*cked up, fact.
I agree if you race bike you may have it for that reason and that reason alone. The price of drivetrains has come down so much now thanks to our European cousins shipping them over nice and cheap, I mean you can get a complete SLX train for about 100 Euros and thats going to last atleast two years. Do we really need XT / XTR / X0 above SLX, no really? It's probably harder wearing anyway........?