Beavertron riders can get away with STI shifters and if it does not get too cold suspensions work fairly well but when the snow hits the plow... an IGH, studded tyres, fenders, and good lights will take you a long ways. I find that most STI shifters don't like cold and don't like getting dirty, friction systems don't have this problem.

I ride a fg mountain bike (rigid), Extrabike with derailleur and friction shifting, and a Raleigh with a 3 speed internal hub through the winter here... my wife rides her Breezer Uptown 8 which is the women's version of transitbiker's rig.

When I was spending winters in Portland I liked the Raleigh 3 speed as it is a bicycle built for wet weather... the rim brakes were fine but drums would have been nicer.