Re the high altitude--as you know, water boils at a lower temperature the higher the altitude. This means quite a bit longer "cooking" (sitting in the cozy) time. A warmer cozy is needed for this as well as to combat the colder air. As others have said, you need a warmer cozy.

My stuff came out fine on my aborted Winds trip (although I never got above 8300 feet at Beaver Park on the Green River) except for the lentils which were a little chewy and could have used another 5 minutes. I think that next time I go high I will take two of those wonderful UL cozies of Sarbar's and put one inside the other, just to be safe when it's really cold. It's either double cozies or wrap the food plus single cozy in my jacket, which I'd rather not do, especially with griz possibly around in the northern Winds. Besides, I'm usually wearing my jacket by dinner time!