Snow Tires FTW!
I was driving cross country in late 2004 with summer only tires (Kumho Ecsta 710s) and got caught up in snow in Montana off the Interstate. SVT motored along still (even up a 6% grade where Semis were passing me cause I only had enough traction to do 30MPH tops) and only got stuck when I got into town on a plowed road and tried to turn onto an unplowed road (all the snow in a pile along the intersection). Was stuck until the car melted it's way through the snow and I got traction.
Next time was in late 2005 with summer tires again (this time some crappy Coopers) and I got stuck in Wyoming at around 7,000ft going over the 7,550ft South Pass over the Continental Divide. Had to have a park ranger pull me over the top with a chain. In the meanwhile, my dad's rental 2006 Cadillac had no problems with all season tires.
So yeah... Snow Tires FTW! And no, still don't have snow tires for the SVT... Other 2 cars do!