I have used both the Hubba and the mountian hardware trango up here in winter. I liked the Hubba better because the ventilation was easier (note I didn't say better!) I had a lot of issues with it snowing inside with the Trango, but I'm 99% sure that was a user issue.

I'm still a little fuzzy on the whole point of a unheated tent in winter unless it is windy or snowing. It doesn't keep you warm and if you sleep under a big spruce tree it will keep the snow and wind off of you (sorry after the whole more snow in the tent than outside (condensation) I've been a bit ... jaded. blush )