The argument FOR a quilt:
-> It eliminates the bottom of a mummy bag, which is compressed by body weight and gives little insulation g=for the weight. Some truth tho that idea and it's why some bag makers use synthetic filling the bottom 1/2 of their bags. It's less compressible.
The argument AGAINST a quilt:
-> It must have straps to hold the edges under a mattress and you need to wear a separate hood. Plus cold air can enter at the shoulder area by the mattress.
In summer I often use my mummy as a quilt B/C it's more like sleeping at home.
In winter I use my mommy AS a mummy. Mountaineers don't use quilts and for good reason, they try to save grams wherever possible.
Quilt users, like hammock users and no-frame pack users are in a cult of their own. But hey, HYOH. (Hike Your Own Hike)