While not familar with the cam specs for the MB from my VW days the difference was made in the mid to high band.
Typically american markets like that low end grunt so the cams are ground to give more low end and less highend (i mean legal speed limit is 65mph in most places anyways)
So if there is a gain it will most likely be to the way the car behave on the higher side of the rpms with a sacrifice to off line performance.
But with what it cost for oem cams might as well go with schrick cams or a set of custom grind ones to get the power you want.