The page in autocar about the different reviewers views on ride quality of the new VW Tourreg make interesting reading imo. It just goes to show everyone has different views on ride quality and noone even reviewers are right or wrong. You have to sample it for yourself to make your mind up.
My view is if you have 18" monza shadows ACC for me would be a must on the mk6 as the ride imo is much harder than the mk5 GTI was but as i said everyones view is different.