Yes, the head gaskets were modified in the areas that were causing problems. Metal reinforcements were added in the areas that were prone to leaking oil, either to the outside or to the coolant passage.

I trust my comments regarding coolant renewals will assist the DIY'ers with understanding the importance of performing them as scheduled, as well the use of MB coolant whenever possible. I've seen a lot of cylinder head damage from other brands, just passing on my exposure/experiences.