I love my down bag. It's an australian 'roman' brand filled with Pyranees(?) goose down. The colder it gets the faster bags get found out. When you wake up and your bag is literally frozen solid from a layer of ice on it and you are toasty warm inside - its a good bag. I see there are some high end man made lofts getting around now which will no doubt be great also. My experience with man made is with the middle of the road (say $120 and 0 deg rating) stuff and it has let me down at the wrong time. The frozen bag experience was at Stanthorpe. I'd be looking for something like a -15 degrees rated bag if you want guarantees of warm nights when camping. Caveat - I am possibly the world's biggest sook when it comes to coldness, so I take keeping warm pretty seriously....'hot' sleepers don't tend to need anything like what I deem necessary to be comfortable.