Opinions outside the realm of the question are welcome.
Fro what I've read, the baffling and down is so high-quality on the WM that it's practically a 25º already. However, the sewn-thru baffles keep the rating down. So my hypothesis is that if you cover the cold spots then the bag's warmth rating rises substantially.
Loft, to my knowledge, depends on how I fill out the bag, and I am skinny. However, it is a concern. I know that loft is gonna be the make-or-break, but given the sewn-thru baffles, I don't think the Ultralamina inside the WM bag is going to come close to the warmth of my old system.
I could buy a 10º bag, because then my system for 30º+ weather would be the 45º and a coat.
My personal furnace means I can push any bag between 10 and 15 degrees or so.
My other option is to spend an extra $100 and get a WM MegaLight and use that as the outer bag. No loft issue, no baffle issue. But I like the weight on the HighLite, and would rather use that.
Any opinions on the HighLite as the outer bag?