For multiday trips in moderate winter temps (think Southwest) or dayhikes in temps above 10F (just about anywhere), this featherweight jacket is the ticket. One tester packed the 800-fill down Permafrost on a trek in Arizona's San Francisco Peaks, at elevations above 10,000 feet and with a windchill near zero, and the protection was sufficient.
The key: The shell fabric is Gore Windstopper, which adds significant warmth by stopping gusts and making the jacket all but waterproof (it's not seam-taped). The Permafrost squishes to quart size. And despite the ounce-shaving, you get fleece-lined, zippered handwarmer pockets and Velcro tabs on the cuffs–but no hood. $249; 12 oz.; men's S-XXL, women's S-XL; montbell.us