I've had both a C6 RS6 and a C7 RS6. The V10 in the C6 was epic (mine was a "plus" with 575 bhp) but didn't it like corners. The C7 was was a fabulous car, traction was incredible in all conditions and it was ok in the corners. I had an epic drive down a certain A road one February, horribly damp and greasy but the RS6 pummelled its was down the road and traction off roundabouts was fantastic. My brother, who has an M5, drove it for a bit on that journey and was gobsmacked at the traction. Downside was the quality of the dashboard which looked the same as a regular A6 and very placticy. Sound can be improved by unplugging the connectors on the valves in the back box, fitting a Miltek (or similar) or removing the centre resonators, but it will never, ever sound as good as a C63! I miss the traction in the wet occasionally but my C63 is way more fun for more of the time, has a much bigger sense of occasion and doesn't need to be ragged senseless to be enjoyed. Also had an early Panamera GTS but won't bore you with that now!