It's a tricky one. Although a small number of s55 have this problem the design is well proven with a lot of BMW R&D and multiple millions of road miles.
So you have to be careful when a small shop comes up with a magic "fix" with no reliability data on such a critical part. As we know a failed fix (broken gear or complete loss of friction) is worse than the OE design simply slipping a little.
I personally have to favour the Lichfield fix, but I'm in no rush to dive in yet...
|