I was surprised to read the EN ratings of some Marmot bags, they rate the bags about 12 degrees lower for men.

I only use down bags. Besides having them in a plastic bag in your pack, perhaps even more important is keeping the inside of your tent dry. Learning to get in and out of a tent without dragging in moisture requires practice. A waterproof shell on a down bag is in my opinion a must. Pressing the warm air out of your bag as soon as you get out of it, then relofting and pressing it out again then stuffing it prevents the water vapor accumulated while sleeping from turning into dampness inside your bag. Preventing condensation inside your tent from touching the bag while you loft it and press it out is critical. Pitching your tent in the sun can create a place to dry your bag. That said, some people will have severe condensation problems in tent next to someone else whose tent is completely dry.
Jim