I've got a HG 20* Phoenix with 2 oz. overstuff, and I just bought an HG 0* Incubator with 2 oz. overstuff. However, I'm beginning to think that my CBS has nothing to do with anything but my own physiology.
I live for REM sleep, perchance to dream. I usually enter a period of quality REM sleep around 3:00 am. and if I'm lucky, I could dream till five am. Coincidentally I usually get CBS during this same time period.
So what if CBS has nothing to do with the shock cord losing tension in cold weather, or all the other advice I've read here on how to regulate your temps, etc., and so on?
According to Wikipedia at: http://en.wikipedia.org/wiki/Rapid_eye_movement_sleep
"Body temperature is not well regulated during REM." This may explain why I always start sweating during REM sleep, no matter what the weather. I could be butt naked or inside a 0* mummy bag, but when the REM sleep comes, I'm gonna sweat. It's a fact.
And of course, when you sweat, there's evaporation, which leads to cooling, which leads to cold butt syndrome or other cold spots. You can adjust the suspension all you want, but that doesn't address the problem that you're sweating.
Now if somebody has a solution to my physiological problem, I'm all ears. And please, Les Stroud fans, don't toss me any "You sweat, you die" adages. Much as I like Les Stroud, that's just an absurd statement. There's probably more truth in "You don't sweat, you die" than Les Stroud's argument.