Yeah, I'm aware that hypothermia is a possibility at those temps, but I'll be moving the entire time at a pretty good clip, so my core temp will be plenty high enough. I've hiking almost daily all winter long and have a pretty good idea of what will keep me warm in what temp while moving.
When I stop for camp, I'll have shelter, hot food/water, a fleece, dry socks, a sleeping bag, and I've decided to bring an extra baselayer too.
So hypothermia isn't really a concern. I just want to make sure that I keep my sanity without overheating.
Unfortunately, the rate I'm going will keep me warmer than I'd like to be in the Campmor jacket, but it's also going to keep me dryer. The miles are what make this a tough decision. If I were going on a short overnight of 5-10 miles per day, I'd just bring the Ether because I'd be done hiking in a few hours and then I'd set up camp and get warm. Since I'll be hiking for a good 10-12 hours, though, it makes me wonder if staying dry is a bigger priority.