I see that being awesome on day trips where you hike, glass, hike, glass. The extra weight penalty on multi day trips is questionable but for cold days this would eliminate packing layers. I think its pretty slick! If your a bit wet from hiking and end up on top of a ridge with a cold breeze this would buy you some more time up there without shaking like a dog shittin a peach pit while sittin behind a spotter. And it looks more convenient than jackets and other layers coming off and on.