Thanks for the post. That was interesting.
I attempted to winter a good many small colonies (4 frames or less) this past winter and the cold did in a lot of them (but not all). They froze in place after about the 4th cold wave. I also lost a few larger colonies due to varroa (most of the bees had vamoosed before they froze). I didn’t treat for mites, I will this year. The cold was more deadly than varroa in my case.