Whether it's 12k or 14k, you could still get spanked pretty hard in the winter on any of the volcanoes. I would be comfortable taking a Volant up in the winter, but a Frontpoint certainly wouldn't be overkill.
Fill weight is one of a few factors when determining the warmth of a jacket. You can get a 650 fill jacket to be as warm as an 800 fill, but it'll be a bit heavier.