I've had a B6 on Eibachs, and a B7 on KW Coilovers. Now I have an S-Line C6, and it is by far the best ride I've had. I wouldn't say it is harsh, certainly harder than the SE C6 I've already had, but I wouldn't say it was too hard.
TBH, the B6 on Eibachs was by far the hardest ride I've had. Jumped about all over the place.
Best thing would be to take a test drive in a C6 S-Line. If it feels to harsh, then the only option is too find an A6 with adaptive air suspension, or an A8 with the same. Plus, if your going from a lovely Stage 2+ B7, you'll find the A6 or A8 completely different. The A6 isn't sporty, its a crusier. Plus, if your going for a petrol, to get the feeling of the sort of power you currently have, you'll need either the 4.2 V8, or the 3.0T V6. Everything else will feel very slow. I have a 3.2 V6, and it feels slower than the 2.0T B7 I had before, despite being 52bhp less.
) other option I'm looking at is the a8..
