All the assumptions that you can't get coverage with a quilt are just that.

Like I said, I get into the 20s fine. And if I weren't comfortable you'd bet I'd be in a bag. I find that it's easier to wrap up in a quilt around camp - I don't care as much about my legs as I do about my torso, and if I had it to do over again I might have gotten a wearable quilt plus the JRB sleeves and had full range of my arms (I have to hold the regular quilt in place).

But, quilts aren't for everyone. There are still a lot of people who believe in what they know, they should stick with what's comfortable for them mentally as well as functionally. Lots of folks look at my gear and scratch their heads - some of them lecture me - I keep using it for many reasons, including claustrophobic tendencies. Regardless of all other considerations, for some the ability to kick off the quilt in a hurry is a plus. Currently, one of my quilts is on my bed. Mummy bags aren't good for that either....

Also, consider: JRB has been in business for some time now. Product line has changed as they go along, adding more quilts, more hammock specific quilts, more versatile quilts... and they still sell cold weather quilts rated down to 0. Do small business sell products that don't sell well? Why do I not see many for sale - used quilts on the forums most likely to reach buyers (backpackinglight, hammock forums)?

Which is not to say you should try one... I'm pointing out things that I observed that led me to try one despite being skeptical. My first quilt is a Ray Way - that worked, and it's about the same weight as one of my JRB despite the bulk of it. But it's just not as comfortable.