I know only what I read,
Some studies in Europe have demonstrated that by spliting the colony between two deeps (dispersing the heat in two cells) that single deeps winter better than double deeps.
This was examplified when weak colonies were placed over a double deep strong colony to convect heat. From what I can glean from the study was the lower hive took on more moisture and froze.
In a follow up, a single deep was wintered on its own to avoid killing a stronger underhive. Strangely, the single deeps (hive for hive) survived better than double deeps.
I think that this is a very interesting point because of two issues. I have read on this board where keepers are increasingly suggesting moving to 8-frame hives and mediums. I believe that this will decrease the weight we need to shift around to manipulate our hives, but maybe a situation for disaster for wintering.
First 8-Frames will provide less stores unless multiple bodies are stacked, and even then, will require the bees to migrate from the warm winter cluster to a cold super, which they might refuse and freeze or starve in deep cold. The more frames in each box the more buffering the winter cluster has from the outside walls of the hive. Also more frames likely results in more stores closer to the warm winter cluster, not in a cold adjacent super.
Second, mediums also create the same migration problem, but also cause the winter cluster to divide themselves among the supers to warm the brood. Unwraped medium exclusive hives also have more seams for possible direct winter drafts than deeps (3 mediums usually equal 2 deeps).
Some people are going to say that cold doesn't kill, moisure does, I probably agree, but cold does stress and stress does shorten the life of any organism. Why not implement equipment that stresses our bees less so that they focus on honey, pollen, wax, and brood production instead?
My two cents, take it with a grain of salt...
There is always more than one way to skin a cat, that's of course if you're into eating cats.