I have 4WD but I find studded tires to be a waste of money.
Makes sense. If I had a choice, and I lived in an area where it would be an issue, I think 4WD is the only way to go. There isn't anything I haven't been able to get out of w/ 4WD. Studded tires just chew up the road.
In the meantime, I'll just sit tight here in the flatlands of the Sonora Desert...and carry water instead :)