Insulating Jacket… what is the most thermally efficient?

Methinks that within reason, it's better to have insulation and shell jackets that are a little too big then too small.

A jacket that fails to protect you from wind chill at the midsection when you bend or move sounds pretty suboptimal. It may also be annoying to wear when sleeping.

So, I would go with the Large — and tuck the bottom with the help of your shell jacket as needed.

Ryan – What is the double layer loft of an Alpine Light Down jacket?

Ryan – What is the double layer loft of an Alpine Light Down jacket?

I'm not sure what the best way to measure loft is, but measuring the sleeve varied from 1.5" – 2". Along the chest I measured around 2.5".

If in doubt I always go up a size, but that's just me. I can't stand restrictive clothing. My UL down inner is just perfect in a men's size large as I have room to be myself!