Hi SL,
I rarely need a puffy while moving - only when it's pretty cold. Single digits is cold to me. If I'm hiking any elevation gain, a puffy over the Aerowool and Athens Core Heavyweight will make me sweat. Flat hiking in the cold with wind is about the only time I wear a puffy while hiking. To me the Jetstream is also a bit too warm for hiking over the aforementioned base/mid layers. My main issue with wearing a puffy as an outer garment is simply the terrain I hunt in. I tend to do alot of still hunting in dark timber. The Kuiu Guide and Sitka Jetstream are much more quiet than the ripstop fabrics in puffy jackets. Plus I have rips in most of my puffy jackets from using them as an outer layer. You'll find the Sitka Jetstream and Kuiu Guide jackets are much more durable and quiet than the puffys I've seen.
As you stated, I do tend to use the Jetstream as an outer shell most of time when I'm stationary. They do have a light insulation but their main function is a wind break.
As to outer shells, I'd estimate I carry only the Jestream 95% of the time. Both it and the Kuiu Guide will shed light rain/snow pretty good. They are not rain gear but do work well for the random precip event. I've hunted it during snow fall and never got wet. I have a complete set of Sitka rain gear that still has tags. The older I get, the more I dislike hunting in the rain. A drizzle is one thing but an outright all day rain usually finds me snuggled in my tent till it quits.
Another consideration. I grew up and still hunt in NW PA. I wear my Sitka gear when it's not raining but usually hunt in Rivers West gear up there due to the lake effect weather. Simply put, it rains alot. Usually misty, light rain events. The Jetstream isn't ideally suited for that situation.
