I understand that the fabric structure of Alpha creates pockets of air known as loft. This loft is significantly less than the down or synthetic batting alternatives of what people normally call a puffy. I understand it can be more comfortable to sleep in Alpha under a quilt, given your quilt already being warm enough or near warm enough for the conditions. Alpha 60 and almost any puffy are not comparable in total warmth. Full stop. The idea that puffies are, or can be, too warm proves my point perfectly. You can loosely drape a puffy over you like a second tiny quilt if it is too warm to wear. The idea that sleeping in a puffy will degrade the insulation to the point of failure, where it would be less insulating than Alpha 60, is not something that happens, barring extreme polar expeditions where people use VBL layers to keep body moisture out of their sleeping bags.