As a cold sleeper, my 32 degree Nunatak Specialist keeps me warm. Slept good in it in a MB bivy (no tarp) on a 19 degree night, wearing microfleece pants, shirt, and hood, MB UL down vest, JRB down sleeves and hood, and 2 pair socks. I am now a believer. I bought it used from someone who needed a longer model.
When held vertically by the side seam and shaken, the down does not shift enough to leave a thin spot. Try that with any bag from overseas.
Have you ever heard any criticism of Nunatak other than the cost? Yes, maybe some bag owner is embarassed to speak up, but if Nunatak products weren't so good, others would be quick to holler about the quality for the price.
Those quilts keep you just as warm as WM products with equal rated temps, but they weigh less. The key there is all the down is over you instead of some of it under you. Buy a used WM bag and have Tim Marshall sew and cut it into a quilt-->Nunatak clone.