Another report for Newbs like myself.
I got my Blackbird last week during a warm spell and was able to sleep in it without any bottom insulation. It was great, the fabric will hold you in any position. Kinda like a dial on a compass, you can turn your body bit by bit, 10, 20, 30 degrees, not just a straight 45 degrees on your side, the fabric will hold you in what ever position you want.
Since then it has gotten cold again, about 39 degrees at night, and I've use different stuff in between the sheets. Using a 1/2 " foam pad is the best for warmth but the worst for comfort! The foam becomes ridged under your body weight producing pressure points, and you end up tossing and turning throughout the night anyways
Using thick blankets work but they keep shifting around, and eventually a part of your body is off of the blanket and it feels like its on a block of ice. And I was wearing my sleeping bag as a sleeping bag and not as a top quilt.
I can't wait till I get a underquilt.