Just because a lot of us use quilts doesn't mean they are right for everybody, but you should get some comfort knowing we all had similar concerns about drafts, warmth, etc and have found quilts have met the challenge.
For me, the quilt was lighter, took up less room in the backpack, and didn't result in any downsides. It has worked both on the ground and in a hammock. I also like being able to kick out a leg while sleeping to help moderate the temperature. Getting the width right is important - if you are broad shouldered, say, then you don't want something too skinny.
On the flip side, you could probably unzip a sleeping bag and use it quilt-like and get the same results. If you got a large enough bag, it could go around the entire hammock to keep you warm, ala Shug's videos on this.
Good luck choosing.