I would not be too concerned by the hype surrounding head bolt failure. Only Merc will know the exact figures, but there has only been about 14 reported cases in the US out of 20,000 + cars in the range. Not seen many reports of issues here in the UK. I would say, based on probability, you are safe looking at pre 2010 models. Extended or aftermarket warranty would cover any issues if you wanted extra peace of mind.
Agree with all the posts above about getting EC Map and Quaiffe LSD
Agree with all the posts above about getting EC Map and Quaiffe LSD