Okay, okay, so you're a skier and you're hardcore. Rah rah rah, get frostbite or die a looser, go hard or go home. And that's all well and good, but once you get to your camp on the third night of your five day ski traverse and realize that you've got to stay in your cold, wet ski boots while you make dinner, you realize that the 5oz that you didn't bring in a down booty could have really made a world of difference. When I go on winter overnights, I generally make sure that I bring these along for this exact scenario. It can make the trip so much more enjoyable.
The FF down booty is great because it actually is comprised of an inner down "sock" and an outer, tougher shell. This means that if you're going on a long trip and want a boot to walk around camp in, you can bring the 9oz of the entire boot. Or if you're going fast and light, you can just take the down sock and bring only the 5oz of weight. I've taken these babies everywhere from Aconcagua, to the Wendy Thompson Hut in BC, to Lake Lichtenwasser to teach youth how to winter camp. I love 'em!
Pros:
Really lightweight
Warm
Inner shell can be removed from outer
Cinches keep things snug
Okay traction in snow without adding bulk and weight
Cons:
Some complain that it is a "sloppy" fit, but if you're wearing down on your foot, it can't be compressed to be effective. For a down booty, I think this is kinda the best you can get.