I ordered the 30 degree quilt with 20% overfill. Just took it out this week-end, temps were not extreme so I haven't really tested it out, but it's common for me to sleep in a puffy and down booties, and I definitely did not need those. Temps were 51 F at 5:30 am, so didn't get down really low, but I was pleasantly surprised with not needing to really pile on clothes--previously I was using a Montbell SS #3, and I sleep on a Neo-Air. I did have a hoodie on, and reached for a hat, but I had gloves, down jacket and down booties ready to go and did not need them.
Partially I'm doing a better job with my hydration and nutrition, but I think the quilt helped too--it's the puffiest thing I've ever seen!
Not sure how that helps you, as our situations are different, but hope it give you some idea of scope.