THEN: I had Pirelli's P6 Four Season's when I initially purchased my Audi A4, but the tread was almost ¾ gone on the rear tires, and probably ½ depleted on the front. Nothing particularly impressive about the Pirelli's I owned. They did look visually appealing, but they were quite loud on the freeway; actually the noise was almost unbearable! They could have been usable for another year easily, but I couldn't deal with the noise. The dealer recommended I get Pirelli's again. I didn't.
NOW: Kumho's are visually stunning (which is a mild factor I consider). They are relatively affordable (they had a promotion which gave me $50 in rebate). 500 miles plus driven on the tires and as such, they are technically "broken-in" So now I guess I can offer my thoughts about them.
I have 235-45-17 Ecsta 4X on 2002 A4 3.0 Quattro. Performance in the snow is the ultimate measure for me and so far, no regrets. NO spinning at all, braking in the snow and wet weather has improved considerably! I do have Quattro, so you would expect that the Pirelli's I owned previously would perform somewhat decently in the snow and wet weather, but they left a lot to be desired! This was another reason why I wanted new tires.
(Just a stray thought..DO get some Bridgestone Blizzaks if you are looking for some nice, non-compromising winter tires. I had them on my previous vehicle, and they were absolutely phenomenal in the snow and ice and winter in general).
Winter tires on Quattro are not necessary for me; the Ecsta 4X works harmoniously with Quattro and ESP.
The tires feel firm and secure on the road (I highly recommend getting them aligned). Noise level is noticeably lower than previous Pirelli's. Road grip is impressive on all surfaces; this translates to smooth, yet responsive handling. Though not typical of me, I can be somewhat of a spirited almost aggressive driver depending on my mood, and these tires are yet to disappoint