I don't think you understand how to drive in the snow. A "patch of ice" will cause you to lose control no matter what you're driving and personally a RWD drive car is more easier to control than a FWD car. AWD / 4WD on a small patch of ice will be better, but on something large where all 4 wheels are on ice you're still SOL.
I drove a '97 BMW M3 in Minnesota (Twin Cities) area for many years. "Deep snow" is a problem just because of the low height, but same for front-wheel drive sports cars. However, any decently plowed road was fine. Starting from zero was sometimes a little slower than a FWD car, but not by much. The traction control always kept me in a straight line. Older BMWs usually had close to a 50 / 50 weight distribution (don't know about modern ones; I would assume so) so it really didn't matter.
I never drove a Mustang so no idea, but I'd say your college age right-foot was more of the problem than the car. Winter tires are certainly better for snow / slush / slippery, but ice is ice. You'd need studs to help on real ice and I don't remember them being legal in MN.
