I slept in this inside a Gortex bivi, on a 3/4 length thermarest light mat. Woke in the morning to find ice inside the bivi where I'd been breathing. I had to crack the frost off the outside of the bivi too. Not sure exactly how cold it was (-5 I'd guess?)but I was fine. In fact, I overslept. If I had one criticism it would be that the cord clips that hold the head and shoulder cords tight, don't really. My head came out in the night because the clip/cord worked loose. Still, for the £129 I paid in the sale, I'm more than happy.
Fill: 600 fill down
Temperature Rating: +10 -20
Price Paid: £129
Despite not using this sleeping bag in the extremes of weather yet, I am very pleased with it. It has a fine nylon inner and outer, and considering the price, you get a lot for your money, including REALLY fat hood (dead warm) and shoulder baffle, footplug etc. By comparison to the extreme range, it does fall under their shadow somewhat, but for your money, It's hard to beat! Highly Reccomended!
P.S. If anyone has any connections with TRAIL Magazine (UK) thern could they ask for this bag to be tested, as I am curious to how their test team would rate this product.
Fill: 600+ fill down, 90/10
Temperature Rating: +10 to -20 degrees C
Weight: 1.6 kg
Price Paid: £200 (UK)