The increased performance will be assymptotic. Personally I stay away from this super high end stuff, because I can't afford it and even if I could, my sense is that it's not so much about the enjyoyment of music as it is about the enjoyment of knowing one has a toy that most others don't. And there is certainly a place in the market for that.
But that's my 0.02
But that's my 0.02