I can confirm that you don't need AWD for winter (aka a C4 or a C4S).
I have one of the first 997C2 since August 5, 2004, and I am driving the hell out of it each day, all year, through snow, ice, mist and a huge number of potholes. Winter tires are a must. But, I didn't went for PASM or 18" wheels to have maximum ground clearance.

I am now at 50.000 km or about 31.000 miles.