44/16 fixed on slick 23s. I actually think it's kind of fun. The skinny tires can cut through a lot of fresh snow, but can also throw you around a bit if you hit a bump or parallel crack or something that you can't see due to the snow cover. The only problem I've had was when I was riding slowly between academic buildings and slipped off the path without knowing it, got caught in the little rut between cement and grass, and got thrown shoulder-first into a large snowbank. Laughter ensued.
I'd say fixed/thin is definitely worth trying.