Stilllearning,
In Arizona I do a lot more hiking then hunting. Nature of the land. I use my hiking/backpacking layers and add camo outer layers for hunting. You are spot on with the idea of two different mid layers. The new active insulated mid layers are intended to be warn while moving. Think Patagonia nano air. Once you get to a spot to glass, you switch out for a static insulation piece, think down. How heavy depends on how your body heats up and how much you sweat. As for the outer, if I'm expecting to be moving through branches, bushes, cactus, I will use a soft shell. If there is any chance of rain I'll have a hardshell in the pack. In Arizona, I've found that a windjacket (currently using the Arcteryx Squimmish) is very useful.
Sense the Jetstream is 25 ounces, I would evaluate it in relation to what I get for the same weight. I would rather carry a Patagonia nano air (14 ounces), Arcteryx Squamish ($150/5.5 ounces) or outdoor research helium 2 ($160 and 6.5), and a stationary insulation piece (had the mountain hardwear ghost whisperer hoodie, not sure what I'll replace it with). The ghost whisperer weighed in at 8 ounces. I can carry the nano air and ghost whisperer, plus either the wind jacket or rain jacket, for an extra 3 ounces. The fly in the ointment is the need to throw camo over the layers if you feel the need. Adds some weight. Still, I'd rather carry a layering system then one big piece.
Now is the time to buy, everyone seems to be having sales on winter backpacking/hiking gear. Good luck,
Peter
