I also like Montbell. I have and love their lightest down jacket, the EX-Light, a less expensive (and probably just as warm) version of the luxury model you're looking at. Do note that they are sized for average Japanese people, who tend to be a bit more svelte than the average American. You may have to go up a size from what you normally wear.

Also note that most of Montbell's insulation offerings are designed to be layered, not worn as a stand-alone item. In addition, to achieve lightness, the shell materials are fragile. This doesn't bother me because I mostly use the jacket for rest stops and sitting around camp, or wear it under either my rain jacket or wind shirt.