Insulation for changing metabolisms

If you don't need it for on the move but just sitting around camp, I'd recommend a non-breathable cuben VBL next-to-skin layer with your current hoody. Will extend it's cold-comfort rating for very minimal weight. I've had a lot of success with them.

I have a Bitterroot and a Roan. The Roan is my everyday winter coat and is a bit warmer than the Bitterroot. I also have a FF Frontpoint that is very warm but heavy and bulky. If you are looking for light, say 12-16oz and warm, I would talk to Ben at Goosefeet about a fully baffled custom coat. I believe there are a couple of BPL'ers that have had one made for them and were very happy. It won't be cheap but when you are miles, or even days from the trailhead and cold, money tends to be less of an issue.

Dave C was referencing sub 12oz down jackets, stuff that is in the sweater weight. I loved my MB UL parka but I agree with him that it probably wasn't as warm as I wanted it. Meanwhile if you go up to a 12oz jacket (basically something with 4oz of down or more) you begin to see real dividends in the warmth/weight department. The GoLite Bitterroot falls solidly into this category and is a very warm jacket for the weight. Now a Mirage with higher quality down and a full box baffling at the same weight is even nicer. Hard to justify with today's GL sale though.

"If you don't need it for on the move but just sitting around camp, I'd recommend a non-breathable cuben VBL next-to-skin layer with your current hoody. Will extend it's cold-comfort rating for very minimal weight. I've had a lot of success with them."

True dat. This last weekend when sleeping out, the low was only about 23 degrees, but decided to try a polycryo VBL shirt under my Stoic Hadron anorak and used a 40 degree quilt when sleeping. Both for hanging around and for sleeping it made a noticeable difference and i was warm enough. Weight was 1.5 oz i believe. It did get a little clammy feeling at first, but by morning it wasn't as noticeable.

(i don't recommend the .7 mil polycryo for this, i ended up ripping it a bit. The 1.2 stuff i think would have been more than strong enough though).

The rab infinity jacket would also probably suit your needs well. Its 7.5 oz of down and 16 oz for a size L. My medium is 15 oz flat and its very apparent that the jacket is about half down (minimal features, light fabric, puffy).

The bitteroot is in a different league of warmth than your nanopuff (insert link to relevant nisley clo thread).

I think the warmth of even the most UL puffy jackets like (Arc Cerium, WM Flash, MH ghost whisper) is a few steps above comparative synthetics, but synthetics are just more versatile. And if you like to spend most of the day moving, they are usually just sufficient enough for the same seasons that you'd bring the down for. What I like about down is the compressibility and the fact that I don't have to worry about how compression will effect long term warmth. To give you an idea on comparative warmth, I was reading form the arc site that the cerium lt hoody at 9 and a half oz tested warmer than their 16oz synethic, the SV hoody. Different purposes for each, but if you're talking about basic backcountry warmth (not multi-day alpine climbing, or spring packrafting in MT) than the best formula is 'just add down'.