I'm sure some would consider the W205 C63 less of an AMG compared to the W204 simply on the basis that the W205 is turbo charged, after all AMG has always been a company that employed N/A engines only. Yeah, yeah I know times are changing and it's all about emissions nowadays and thus the turbos but according to many motoring scribes there's still a preference for non turbo 911's and for older N/A Ferrari V8's for example.
So, I'd argue the W205 is a lesser AMG (if no doubt awesome in it's own right) compared to the W204. After all a faster and lower emissions car doesn't make it a better performance car in the eyes of many including myself. Not to mention that there's possibly far more cost savings to be had sharing a similar basic V8 in non AMG versions thus the AMG uniqueness of the C63 is lost even further to an extent.
Don't get wrong I'm not knocking the new C63 just saddened at the loss of large displacement and the introduction of forced induction.