I recently got a bivy sack from Borah Gear, the snowyside 2. It has eVent top fabric, waterproof floor and weights 12.9oz. I tried it out last night on my deck and it worked great. Not the most challenging of conditions given how warm it was, but still. Low of maybe 51 with 92% humidity when I woke up this morning. Slept with it open as there were no rain or bugs. There was a tiny bit of condensation on the flooring material on part of sides but that was it. Just a slight bit of damp if you ran your fingers along it and I was sleeping in a very overly insulated bag for the temperature (golite z10.) It fit my long cushy air mattress with no problems, as well as myself, with a little extra room in the top. This is the first bivy I’ve used so I don’t have anything to compare it to but I’ve certainly read enough horror stories about bivys and water to be optimistic about the snowyside 2 so far.
A bit foggy.