For winter travel I always switch back to lexan nalgenes; the wide mouth is invaluable. At night, leave your nalgene upside down so it freezes in the bottom of the bottle. If the top freezes, you can still break the ice because of the wide mouth. I used to use the cloudy white ones in the winter but eventually killed one after multiple fillings with hot water to help keep me warm at night. The lexan ones just don't die, no matter what you do to them and for winter, I think that's worth it.