Tvolcano wrote a review of MontBell Ex Light Down Jacket - Men's on January 11, 2012
5'9 150 size small is a nice fit. This jacket is a great layer with icebreaker 260 in very cold weather. I don't know why people wear baggy jackets that don't look fitted. You should get this just for the ease of packing/weight. You will stay warm and if you start getting hot, easy removal and storage.
I've camped out with big agnes sl1, western mountaineering alpine light, icebreaker 260 top and bottoms, MONT BELL ex light in 13 degrees, windy, snow and did not get cold. 5:30 am tear down, paddle trip was early, but not cold. This jacket is a great layer and performs well in all situations