If you're going to go into that weight class, this is a better jacket : Much warmer, better at staying dry http://www.featheredfriends.com/...Lt/HoodedHelios.html

the ultralight down inner is just that- a layer. It's other redeeming feature (for me, at least) is that it's sooo packable that I'll actually have it in my pack, even when weight matters.

i currently have

arteryx ... atom lt, fission AR, gamma lt, gamma sv, beta ar, stingray, tau lt, solano, various fleeces

mammut ... andalo

OR ... chaos

Marmot ... various fleeces

westcomb .... kokanee

EB First Ascent ... downlight vest, downlight sweater

and a whole ton more ... lol

I love love love my Arc'Teryx Atom LT hoody. Stretchy, breathable, warm - I can wear it both over & under stuff and it's still comfy, but mostly I just wear it alone. Think lightest puffy ever. It's not waterproof but I've worn it in light rain with no problems, it still sheds water to a point. It's pretty rugged too - much more so than it appears. The cuffs are great - no sleeves riding up as you climb/belay/whatever. I've had mine going on 2 years and have worn it everywhere... Damn I feel like a commercial.