So I'm in the market for a down jacket with a hood. I've read the state of the market report on ultralight jackets which does an excellent job of comparing the different jackets scientifically, but it doesn't really give any good frame of reference for how warm the jackets are. For example, the Montbell UL jacket seems to get good reviews, but then I've read that the Montbell UL jacket is only warm until the 40s, which doesn't seem very warm to me at all except for relatively low altitude summer backpacking.
I'm looking for a hooded down jacket that will keep me warm to maybe 10-20 degrees sitting or standing around. It would be the type of thing I would use on a PCT thru hike. During my time in the Sierras last August, it wasn't unusual to be 20 degrees in the morning if you were camping above 10,000 ft, and I imagine that the early season PCTers have it a bit colder. I imagine I would layer it with a long sleeve base layer, possibly a windshirt, and a hardshell on top for maximum warmth. Is the Alpine Light what I'm looking for? Or am I completely missing something?