Quick summary: warm and comfy on my back, legs and feet with the JRB BMBH and Mount Wash. UQ, and extra comfy all night on side and back. Below 16*, even with significant layers, need a bit more than the Golite quilt on top.
I had one of the best, most comfortable cold weather nights ever in a hammock last night, and definitely the best one ever in my back yard. Over the last two years, most of my back yard testing attempts have been sabotaged by my inability to sleep. But maybe because I was so comfortable in addition to unusually warm, I fell asleep pretty quick and slept about 4 hours straight, then got back to sleep for a couple of more hours. Now that doesn't sound like much compared to the 12 hours I have been known to sleep on the trail. But in my back yard, I typically give up and go in at 2 or 3AM when it's obvious I am not going to sleep. I don't usually do all that good in developed camp grounds either.
About 1030PM I put a hot water bottle in my hammock. I noticed that the underside of the tarp and outside of the UQ had a heavy layer of frost on them already. About 11pm I sacked it at about 22*F with a forecast for 15*. I accidentally got my jacket a little damp on the back by contacting the frost on the under side of the tarp, and caused it to "snow" a little into the hammoc as I knocked some frost loose. I had on a few layers top and bottom a balaclava and hood on my jacket. I pulled my Golite 20*( maybe just a touch optimistic rating, but close) quilt over me. I had PG booties and space blankets and pads handy, but used none of them. Apparently I was out pretty quick for me. But I realized after 15 to 30 minutes, and just before passing out, that I was very warm, and very aware of a nice warm sensation on my back. Though as I warmed things up with body heat, I would occasionally be aware of cold butt syndrome. But that went away pretty quick.
I woke up about 330AM. I think probably because I was just barely cool, definitely no longer toasty warm. Though I think it was mostly top side coolness, but I'm not certain. I decided to get on my side and pull the quilt up over most of my head ( it's not long enough to completely cover my 6'1" frame, sadly, but will cover all but the very top). At this time I noticed that the top baffle( top several inches) of the quilt, the Pertex Endurance section, was quite wet from condensation from my breath. No matter, I quickly warmed up quite nicely and went back to sleep, feeling very comfortable in all positions during this night.
I woke up again about 430AM. Once again aware of being just slightly cold. It felt like it might be top as well as bottom slight cold. I debated putting in a pad or my space blanket. Instead, I decided to get up and pee and get a warmer bag. Pretty soon I was back in with an old PG mummy NF bag rated at 5*F, but this time no hot water bottle. I got on my side, pulled the wonderful hood over my entire head and made a small breathing hole, and was instantly nice and warm. Then I decided to get on my back, which meant getting in the bag. ( the hood really interferes with quilt use with back sleeping, and I get a poor shoulder/neck seal). So I got in, zipped up and cinched the hood and neck collar. Luxurious warmth, top and back, off to sleep. Got up about 7AM, went in and made coffee. The official low was 16*F at a nearby weather station. My thermometer showed about 11 or 12*.
My PG bag was also pretty wet at the area near chin contact, but that seemed irrelevant to warmth. ( a neck gator might have helped with condensation, but I did not use it). So with the 27 oz Mt.Washington UQ, I seemed good to go at near to 10*, for sure as low as 12-16*F. Once warm enough on top, I was just fine on my back, legs and feet, on my side or back. As I had been for the first 4 hours with the lighter quilt. This is a really good set up, and I think I could have gone a bit lower and been OK. I was impressed that I never had cold feet, even in the light quilt, and with just one layer of wool socks. And no matter how I rolled around, there were no cold spots- just some cool ones for a few minutes.
But I might have been just a tad past the limits of my 20* Golite quilt, even with my several extra layers. Especially once I got things wet with my condensed breath. I wasn't bad cold, but I was sure on the edge. When I got the quilt inside, it looked like it had lost a good bit of loft in that small uppermost area that was obviously wet. It also weighed 3 ozs more than normal. I don't know if that is a lot. But my heavy PG bag handled things with ease, condensation or no condensation. Too bad it is heavy and bulky.