I got the RS3-a. The S is the summer tire, while the A is an all-season. I can't speak for the S variant, but most slush just rolled right under these RS3-a tires.
Before inconsistent slush and snow would make the car do a strange lateral shimmy, like it was skating those grates they use on bridges. These tires dig right down to the pavement through most any kind of snow. I was very impressed. I noticed that my gas mileage has gone up tremendously too. Before my average was 19.8 between fill ups. I've got it up to 23.5 so far, but I can tell that while cruising its way easier to keep the mileage computer above 25. Before I was excited when it would go over 20. Everything about the car is better. Launches don't have any shudder to them (Something I didn't even realize was happening before), and turns are just all around more comfortable. They feel much easier, physically, on the car itself. I couldn't be happier.