Sorry, I've been too busy driving lately to haunt the forums as much as I was a month ago!
Yes, I've had my Model S in Manitoba for both recent horrible cold snaps (-34°, with a "standing still" windchill of -45°). Other threads mention this, but the only issue is 'fogging', which is not a problem if you use your climate control properly. I'm from the Steinbach and have driven to Winnipeg and back multiple times in poor conditions with no problems at all. Battery use is higher if you keep the heat on, but worth it IMO. Continual driving is better for range than stopping and letting the car cold-soak for an hour or two. The heater does not have a problem keeping the car warm, as long as you keep it on a higher setting; I have been getting too hot inside, so I use manual settings so I have full control.
The other thing to be aware of is regen limitation when the battery is cold. It's clearly marked on the power meter, and while it's surprising the first time, it is easy to adjust to. The only qualms I have is taking it out during a heavy-snowfall blizzard; and that has more to do with lack of clearance and 4wd.
I'm the one bringing my car to the MEVA meeting, I hope you can come out! It will put any concerns you have to rest, I'm sure.