While pro's and racers may have different bike set-ups for mountain riding/events, I don't know many of the rest of us, mere mortals who do.

I mean beyond the obvious, which would be a different gearing/cassette set-up, what else are you going to do differently?

Granted as light a bike as possible is ideal but then there is a pretty linear relationship between cost of a bike and weight....more $$$ = less weight, mostly.