Part of the problem with any down sleeping bag or quilt is the compression of the down under the body weight. If you can keep the sleeping pad or air mattress tightly against the sleeping bag or quilt when you turn on your side or over you are supposed to have little or no air leakage for a cold feeling. Having not used a quilt though I can not comment.
But with the concern of compression of all of that down under the body (and I do have 2 Feathered Friends Down Sleeping Bags) I opted for a Stephenson's Warmlite DAM (Down Air Mattress) which I still have to put into service. My DAM weighs 20.2 oz and the pump sack weighs 2.8 oz. So in the DAM I would have uncompressed down below me in air mattress tubes which inflate to 3-4 inches. I am not sure, but I believe that Stephenson's uses 800+ goose down. So following this option, though it is perhaps a bit heavy, you would have down above you in the sleeping bag or quilt and down below you in the DAM. If you considered this option and were able to lock the sleeping bag or quilt to the DAM you could use less down in the quilt or sleeping bag and be quite warm.