I lived mostly in Quebec or Ontario most of my adult life, and since day 1 of my first car, I used dedicated winter tires - either Blizzak or X-Ice series.
Starting about 5 years ago, I started using all weather tire - CC2, and I am no longer into winter tires anymore. Under serious conditions, winter tires are better for sure, but at least I have an option to not drive in those conditions. Outside those conditions, the difference is close to zero, and during border seasons when temperature gets hot for short bursts, I no longer worry about wearing down tires too fast. I finally have an option to drive south in the middle of the winter without changing out tires, which also creates some risks as climate varies a lot during this drive.
As for BMW X3 vs MY for winter driving, hostely I cannot tell the difference in terms of winter performance when identical tires are used (both on CC2). I could tell the difference when X3 was using X-Ice vs CC2 (initially used as a 4-season replacement), but I could also clearly tell the difference between CC2 and 4-season tires under slippery weather.
All of my friends who own Teslas have switched to either CC2 or Hakkas. They are located in Montreal, Toronto, or Ottawa.