I'll go first, family does alot of outdoor camping in the summer. Oldest boy is in Cub Scouts and is doing more camping all year round. So we needed sleeping bags for the colder weather. I purchased two 4 piece military sleep systems (the older model, not the new 5 piece ones) off of www.ammocanman.com
the bags have a stuff sack, a camo bivy cover, a black cold weather bag, and a green light or patrol bag. As far as the website they shipped them in about 4 days at standard shipping, eveything was in very good/used shape, they needed laundered right off as there was small amounts of sand in the compression sacks of both, but they did include a free sleeping pad (military/very thin). So we were happy there, we went camping this past weekend with the Cub Scouts and the first night it poured and was down to about 40 degrees, I used all 3 bags the bivy, black, and green and was very comfortable, it also poured that night and several times throughout the night I had to get up and go assist boys with tents or tarps, climbing in and out of my tent rain got in on my sleeping bag, but I was very pleased to find that the bivy cover truly is waterproof and the bags underneath stayed dry. The second night no rain, however the temp dropped to 30-34 degrees with a frost advisory/freeze warning. Once again I was very warm, toasty even in my bag, but the big test was would the 9 year old boy be warm and comfortable sleeping in 30 degree weather, he was in a different tent with other boys but had no issues either night and said he was warm throughout both nights. Factors that could play in, both tents we used were actually summertime tents so not really built to give added heat. Also both the boy and I slept in t-shirts and sweat pants as you never know when someone will wake you up in the middle of the night, but not enough layers to really add alot of warmth or make us sweat. Also the bag is big and heavy, probably not designed for lightweight backpacking but I'll put up with the weight for the warmth and waterproofness of it for cold/inclimate weather. Another thing I found cool was I read that in the military they call the compression sack a stuff sack because you just "stuff" the bag in there, I'll admit I was initially worried about how big a pain it would be to roll up all 3 bags and get them to fit in the stuff sack, but when I heard this all we did was put both bags in the bivy and stuff it all in the sack, it took less than a minute then the sack compressess down around it. Looking forward to spring/summer and just using the different bags individually. All in all it was easy to work with, warm, has big heavy metal zippers, and I was quite pleased. We got ours used for $85 dollars a piece plus shipping (limited budget) and I am happy and would recommend the old 4 piece military sleep system as a good one for outdoor/survival.