The Marmot Mountain Down seems durable enough but still a little heavy and only 650 fill down. The Patagonia Fitz Roy is out because it only has 6.5oz of down and snug sizing (from what I read). The Patagonia DAS with 170g Primaloft does not seem warm enough for -20*F. Sure, it has the benefits of synthetic and has belay parka sizing to go over everything but I could see myself freezing to death wishing for more with it.
Again, my layers would consist of a wool t-shirt, R1 fleece pullover, and the parka. I would like the parka to fit over my shell since I will probably have it on anyway.
The Rab Neutrino Plus has caught my eye: 30d weather resistant Pertex Endurance, 10oz of 800 fill down, baffled construction, double zip for use as a belay jacket, a long cut for more warmth, all for about 27oz.
Personally, I would prefer the 30d Pertex and double zip of the Neutrino over the 15d MEC Reflex. Sacrifice 2 more ounces for less down and more features/durability? Would 10oz of down with my other layers be warm enough for -20*F? One of my favorite local gear shops offers Rab and would appreciate the business too…
