Pros: Great warmth to weight ratio, packable, DWR works, wind proof, breathable, replaces a hard shell in many cases.
Cons: Gets smelly quick.
I ended up getting the nano hoody at an After XMAS sale. I like it better than the shirt for "all mountain" use, and I see why splitter speaks so highly of it. It is slightly warmer than the shirt and think it replaces a hard shell and other insulation layer in my pack for most fair weather days in the mountains,and day tours.
I tried skinning in it today (it was single digits and breezy) and like the shirt, for me, it is simply too warm for the skin track. After skinning in it for about 30 minutes, it stinks and needs to be washed.