I expect some of your opposite experience to mine may actually be the "winter of my discount tent" - my cheap nylon tent is exactly that - and small roof vents - I've seen those old eldorados and there is probably a lot of difference to be had even in the amount of ventilation you can get through the eldorado, which is probably a much better thought out design than a 20 year old canadian tire dome tent <img src="/forums/images/graemlins/smile.gif" alt="" /> - of course if you're covered in 4 feet of snow you're actually far less vulnerable to freezing - the snow will insulate you so you're
only at 0 C right at the tent wall .

I expect some of the difference also may be your weather - My deep winter experiences
are *bone dry* and cold. so frost aggressively forms on everything when there is any kind of moisture, and there is almost never a significant amount of snow on my tent, so there's
no insulation factor between it and the outside world. I also don't have a "good" tent
for this type of use like your eldorado. However I know I've had frosty ceilings even in canvas tents in the mornings too. So back on topic, while I agree waterproofing is mostly unnecessary, I personaly wonder whether "breathability" of the fabric matters as much as ventilation and good design for same - i.e. how much of your success with the eldorado is the todd tex, versus just good design and venting. In my experience it doesn't, in my weather - but itsounds like you see different - are we really talking about regional weather
differences in the amount of humidity in the air when it's cold?