Marmot Helium MemBrain
Source: bought it new
Price Paid: around $350 on sale
Great lightweight 3-season backpacking bag.
Have been down in the mid twenties with no extra clothes on, very warm, very roomy mummy shape. I'm 5'9" 200 lbs with plenty of room, packs down small. At a shade over 2 lbs great bag for backpacking.
Have had the bag for about 4 yrs with no problems at all. Thanks.
Price Paid: $367
This thing is like a dream. Waterproof outside, breathable and comfortable inside. The MemBrain lining, although I'm not sure if it's worth the extra money, feels amazing.
After camping while smelly and sweaty, this bag seems to remain clean, which means you'll have to wash it less and it'll last longer than other bags. The down is very lofty and lightweight, like sleeping in a warm cloud, and packs down very small.
Quality seams and no leakage; I was worried at first as I saw some down on the bag when it arrived but it must have been from the factory since I haven't seen any since.
I'm 6'0" average build and got the long version and it fits great. I find that even though most regular bags supposedly fit 6ft people, the hood won't cover your head enough. Found at Basegear.com with a 20% off coupon for $367 ($430 normally at many of the cheapest places).