The RS6 is a beast. I saw one last night. I don't understand the type of person that would buy one though. Do they think, well I need an estate car, but I want buckets of performance too, or what? Surely, if you could avoid the estate you'd get the saloon any day and if you'd got the money for one, what do you need boot space for? You're probably not a guy that's going to go down to Ikea for a flat pack? An estate is supposed to be practical, yet a practical 572bhp car?
I'm also quite partial to the Chrysler 300c SRT 8 Estate. I wouldn't have one over the audi though, but the normal 300c estate appeals to me because of all the car you get for your money.
http://www.topspeed.com/cars/chrysler/2007-chrysler-300c-srt-8-estate-ar17454.html