Well, the FlexRay response time of 2.5 ms is surely contributing to make the feedback of all systems (damping, DSC etc) a lot better. As you know, the enemy of grip on slippery surfaces is not the weight (purely physically) but slow adjustments of the different systems. This is why Volvo with the Haldex III version has no chance against for example the BMW xDrive system. The Haldex system shifts 90% of the torque to the front wheels and is able to theoretically shift over 50% of the torque to the back wheels in 1/8 rotation of the wheels. This 1/8 rotation is a disaster when it comes to grip on slippery surfaces. You can just read all the test of 4wd systems and you will see that they all come to the same result.

I was testing the grip i Sweden this year between a 2004 E53 and a XC90 in different gradients and different friction coefficients between left/right. There were identical set of tires between the cars and the difference was huge. When the XC90 was standing still, spinning, the E53 was gently finding grip in almost any situation thanks to the fast regulating xDrive.

In for example "OffRoad" 2/09, different systems were compared and the X6 had the highest speeds in slalom and exacly identical time in acceleration on ice uphills like the Landcruiser. The Volvo XC 60 (with Haldex IV) and Jeep Cherokee had no chance in any of these disciplines.

Regarding differences between E70 and E53, does not the E70 have a standard setup with 60% torque to back and 40% to front, while the E53 have 50/50? At least this is what I can recall, Audi has followed and changed their successful Torsen 50/50 to 60/40 as well, which gives a lot better drivability on curvy roads (less understeering).

Only my opinion...