We overwintered 6 hives, 5 wood (cedar no insulation) and 1 poly, all survived, the poly was the 2nd slowest to build up and we put that down to the queen in the wood one so disposed of her. I know there are arguments for poly etc. but can't for the life of me understand why somebody wouldn't sell bees for either box, crazy.
Maybe with the insulation properties of the poly keeps the temperature more stable but the hive doesn't heat up the same as a wooden on with a weak / infrequent sun, so the queens in the wooden ones may feel the change coming sooner and start laying earlier. Just a thought, no doubt someone has measured it and has much more experience will be along soon to tell me I'm talking rubbish but seems more than a coincidence. BTW the queen in the poly is laying very well now, just started later.