I can't say for certain on the Benz, but on the cars I have a lot of experience on, I've seen changes in the torque specifications for the cylinder head evolve over time with changes in the technology used in the head gasket. Most head gaskets come with specific instructions from the manufacturer of the gasket and they are what I follow. Few require retorquing after run-in and most use protractor torquing for the final stage. One caveat is that most of the engines using protractor torquing are using stretch bolts so it's conceivable that you would need to change the bolts to obtain the best results.