You: would rather risk a night in the rain than carry a tent. Your bag: the Shield, which is literally designed for a wet bivy, thanks to a small face opening protected by a waterproof, stiffened visor. The brim overhangs your face down to nose level and shields you from wind-driven rain and snow. The bag itself is covered with a seamless shell of waterproof/breathable laminate.
The rest of the features are what you'd expect from a bag that costs more than $500 (ouch!). Plenty of 800-fill down and a tapered, efficient shape delivered "real sub-20°F warmth on a frosty November hike of Bryce Canyon's Under-the-Rim Trail," commented one tester. Twin half-length zippers on each shoulder make it easy to read a book, but we wish the two-way zips had dual slider toggles to facilitate opening from the inside. $530; 2 lbs. 9 oz.; 15°F