I also purchased a Cayenne about 3 months ago that came with the 21' wheels, and Pirelle P Zeros. I live in Denver and the first threat of snow after my purchase led me to buy a set of the DSW's. I ran those for about 3 months in rain and 70 degree heat...oddly enough no snow...However, I will say the Conti's are a much smoother ride and are very quiet as well. The sidewalls are a bit softer than the Pirelli tires which is to be expected since the Pzeros are summer only.
When pushed into cornering, the Conti's give a bit, but it's very predictable, and only really noticeable on rapid directional changes and at higher speeds.
Never thought I'd like those tires, but am impressed.