I'm about to go through my fourth winter with my 944 with no snow tires. All the winters have been in Indiana (where I went to school). There have definitely been some interesting days (and nights), but I've only gotten stuck once (at the worst possible time)
. You just need to be careful, and not drive when it gets real bad out.
This winter I'll be somewhere in the West with the car. I'm driving on Friday and Saturday from Minneapolis to Salt Lake City for a new job. I don't plan on taking on any snowy mountain passes with the car.
Driving a 944 all winter can be done, just be careful and be prepared.