No, I havn't driven an S6 but I beat the crap out of its lighter predecessor the 200 20v and it handled like poop too. Was a fun car, dont get me wrong, its just not the cars strong point.
Have you ever auto-x'd the car or really done anything motor sports wise with it? If not Id love to meet up with you and auto-x or even hit up a track day. My S4 is a pretty comparable car, you just have more Leg room . When searching for my current car the URS4/6's were the other option. They are very nice cars, just dont handle like say.... a Mini for example.