Just wondered what forum members views were on these two. The Nunatak is lighter, but maybe there are some advantages to the Western Mountaineering bag?

I also will be interested to hear what others think of this. I am looking at the WM UltraLite And the FF Humingbird as i am pretty small at 5-10 146lbs give or take. The Ultralite looks like the same thing to me a the Alpinelite just a bit more narrow?

The WM Ultralite would be more comparable to the Alpinist... 59" girth for Ultra, 61" for Alpinist, 64" for Alpinlite. Also, 14 oz down Ultra, 11.5 oz down Alpinist, 18 oz down Alpinlite.

The Ultralite is 2" narrower in shoulder girth and uses 2.5 ounces more down. Given that it's using more down in less space, it should prove to be a warmer bag. That said, the lightest Alpinist is 21 oz versus 29 oz for the Ultralite.

Crazy that there's a half-pound weight difference between these two. Subtract the 2.5 oz extra down in the Ultra, you're left w/5.5 oz of difference in the shell. From what I can tell, the Quantum Nunatak uses is about the same weight as the WM shell fabric... so the shells should theoretically weigh about the same. I'd guess that the Nunatak eliminates the draft collar at minimum. Perhaps even the draft tube? But that wouldn't make much sense. Whatever... bottom line, there's a definite weight savings in Nunatak; I would guess that the Ultralite would be warmer. I'd be tempted to try the Alpinist with an overfill.