Top Gear recently pitted the new Aston Martin DBS Superleggera in a 1/4 race against the AMG GT R. Despite the Superleggera having a significant advantage on paper, and being far more expensive, the AMG still looks to be one of the best valued premium sports car. I do feel like a lot of the problem was the driver however, as there is no way a 138hp advantage would translate to this kind of result.
Aston Martin has been trailer behind for awhile now imo. Considering how many different components are outsourced, it's going to be tough to get everything to sync up right. Really don't see the point in spending nearly double the money on the DBS.