Our researcher Seppo Korpela got 10 Macedonica queens. Their hives all died first 5 and then 5. All starved in winter during 2 years. When I calculated the amount what the hive could spend during winter months, it was 80 kg. There is no reason to keep such bee strains.
The first rule in our climate is that the colony starts to winter in right time. It cannot follow weather temperature because we may have good weather and then it changes permanenty so bad that bees cannot come out. Our bees do not make cleansing flights during winter and they are not feeded every month.
I have had colonies which are not sensitive to local weather and they were often near to die. And many have died for brooding.
A Langstroth box may contain a certain amount of food and that will enought to next May when willow starts blooming. Like our professionals say, that they do not go into wood their hives from snow, because they have not time to look them. Forest roads are often full of snow in April, and they cannot drive with cars there.
Hive must have allways 5 kg store that beekeepers has time to look after them. It is 2 weeks food in Spring.