Uber Bivy Field Test Report. I just completed the High Sierra Trail where my son and I each took a MilesGear Uber Bivy for a 5 night test. We didn't get any rain during our trip to test the water resistance of the bivy, so cannot report on that aspect. Our highest camp site was 11,500' and typical over-night temps were in the upper 20's to low 30's. Pros: I sleep warm, so the extra roomyness was great for someone like me that starts off the night by draping the sleeping bag over body vs crawling right in to the cushy down, then adjusting as the night gets colder. It was also nice to turn over during the night without rubbing the sides. The bivy size was really appreciated in the morning when I was sitting up and putting on my down sweater and socks without getting out of the bag. The extra room inside(air-gap) tends to keep the inside of the bivy much warmer than my OR bivy, so I ended up propping the end open over-night using a 1 liter water bottle. Cons: On the down-side, the ground cloth supplied with the bivy did not work for me, because it was too large and too slick. I'd just toss the GC supplied and use a large trash bag to protect the underside of the bivy. I contacted Miles and told him the stuff sack works great when the bivy is new, but after a few nights of use and getting crinkled up, it became more difficult to get the bivy rolled up tight enough to get it back in. SUMMARY: I slept warm and comfortable without the physical restrictions of my regular bivy, so I give the bivy a double thumbs-up.