Last time I drove in the snow almost 2 years ago, it was just over 1 inch and I had trouble braking to a stop without sliding, but otherwise I had no issues.
I drove a few miles in the snow last night with my performance summer tires. I never slid unintentionally, but then again I kept it under 20mph most of the time and it was under 1 inch of snow. It was just fine. I didn't even need to start off in 2nd gear since it the rear wheels did not spin out in 1st. 14,000 miles on rear tires and 5000 miles on front tires.
Off topic. I just drove this the other day. 05 Audi TT Quattro 1.8T 225HP 6 speed manual. 116k miles. Great condition and drives like new. PM me if interested as it is for sale in Philadelphia, PA. Has Intake and BOV and LED lights. Very clean.
FYI, I was driving home from work when it started snowing. I wasn't driving in snow because I wanted to.