I don't wrap my hives any more. Feel it caused to many moisture problems. I use SBB and top entrances, only one Hive w/ SBB is now wide open. I do place 2 inch rigid insulation on tops of all my hives. I've lost two small colonies (caught swarms) so far this winter and take responsibility for failing to dump or combine them. They were too weak, lesson learned.
I agree with Be a Bee, this hasn't been a very cold winter for us northern beeks "yet." Our regional weather issues affecting bees began with a very warm November, causing bees to feed on stores they should be eating right now. I did feed all of my hives dry sugar before closing them up. Waiting now for a day above freezing to check and feed, it may be awhile I'm afraid.