I tired out my blackbird last night - the first snow of the season.
Temperature didn't seem to get much below freezing (32 degrees).
I had a CCF pad and thermarest type pad in the sleeve and was mostly warm, but could feel a narrow strip of cold along the center of my back. I was using the sleeping bag mostly like a blanket/quilt and it was a little warmer when I pulled it under me - though I know it was mostly compressed at that point.
I've used the HH with its undercover and a pad inside that. I think it provides a little more of an air gap - but not air flow - between the bottom of the hammock and outside air.
Without using a special under-quilt - just using a pad in the undercover (of the HH) or sleeve (of the WB) - I wonder what other's experiences are.
I do realize it was my first time in the WB BlackBird and I got in it at night, in the dark. So maybe something slid around inside the sleeve.
Next time I'll try the ccf pad in the sleeve and the narrower thermarest directly under the bag.
This was the coldest night I've been out and comfort-wise, the Blackbird was great.
I don't plan a lot of winter hanging, but it seems to me that if I can cut the airflow (convection heat loss) under the bag, it would be warmer than a tent on packed snow. Maybe not.
Please share your insights.