I use lightweight hikers in good weather, and shift to Limmers as it gets colder and the snow arrives. When its REALLY cold, I'm in Sorels with vibram soles. I keep thinking about "upgrading" my winter boots, and never seem to get around to ditching the Sorels. Yep, they can be loose, but with enough socks material, and proper fit, they can be made to work well.
Sorels with vibrams offer plenty of external support for flexible crampons. I've used them with crampons for 25 years of winter trips and never had a failure.
The Sorels work very well for winter overnights. Wear them around camp until its time to hit the tent. If its REALLY cold, they come into the sleeping bag. If its just cold, I lay them flat, with the tops touching and the soles pointing outward and use this as a cradle for my sleeping bag hood. Nice cradle for your neck and head and the warmth keeps them warm and flexible the next morning.
As I mentioned, I keep looking for a better alternative, but the combination of cost, extreme warmth and the fact that my crampons fit them keeps me wearing the Sorels.