I would buy an RS6 Avant immediately and have already told my dealer the same. In fact, I would have already bought the E63 AMG Wagon, warts and all, if it had AWD. Alas, icy roads + long drives skiing with family in tow aren't in the cards without AWD. I detest my SUV, but it's functional.
My favorite RS was my Sprint Blue B7 RS4. Loved everything about it -- except the fact that it couldn't cope with three growing boys and our need to escape skiing on the weekends.