I am wondering what this is all about?: are we speaking about MFD photography here or seriously thinking that such a show is the main concern/problem of photographers when they wish to work and reach high IQ?
I can assure you that there are other issues to be considered.
This being said, Sinarbacks (and I guess other manufacturers' backs as well), do work in low temperatures as well. But I can tell you, for having experienced it myself, that it is not the digital back which is your concern then, but the batteries and .... your fingers!
BTW, a short story of a Sinarback user in Manila: 3 years ago his studio burned down. The Hasselbald was partly melt (with the Sinarback mounted on it), the fishes in his studio aquarium were boiled, the Foba stand was distorted, ... He was thinking that the Sinarback was dead. In fact the fiber optic cable was melt as well. I visited his studio and changed the cable, and this back worked fine and normally. To be sure, that really nothing wrong had happened, I took the back with me to the Sinar factory. I did not mention what happened and just asked for a check. The technician called and asked me what happened since he found the back to have a strange "smell", but nothing else wrong! Since then the customer is using this back normally.
Best regards,
Thierry