As mentioned there are other pads available as usual already proven on the SLK and they seem to have even a slightly positive effect on the already not too shabby brakes.
Another thing seems to be which wheel cleaner/tire shine is used.
It almost seems as if the brake bias is just a hair too much front over rear. That would explain why the fronts are getting sooooooo dirty soooo quick.
Due to the rather high speeds possible and in order to avoid rear instability this is probably the desired setting however.