Any experience with marmot's Membrain sleeping bags?
I bought a CWM -40 sleeping bag a while back and didn't notice that it had this feature.
Personally I have avoided waterproof sleeping bags as I primarily use a tent and am more concerned with moisture from my body than from outside. If I need more protection I'll use a bivy.
My main concern is that on multi day trips I will have a lot more issues with moisture in the insulation than on a non waterproof bag. Has anyone used membrain or similar bag and noticed any difference in moisture buildup over the course of multiple days or is the difference in breathability a non issue. Obviously moisture will be an issue in cold weather regardless, but I'm curious if a non waterproof bag will do noticeably better.