I am going to address the weight issue head on because I don't think people understand it.
The weight has increased, but the grip and lateral traction has been increased commensurately. The car can corner very well as an M Car should. It isn't a straight line car like the E63, CLS63 or S6. The M5 loves corners.
2014 Porsche 911 Turbo S
2015 Mercedes-Benz C300 Sport 4MATIC