In a hammock, probably, on the ground-no. Simple reason, when I used my quilt last April i was able to clinch it around me where I wouldn't lose heat and let cold air in order to stay plenty warm. However, I was able to feel a little cold air drift into tiny gap between sleep pad and quilt. I covered that gap with a piece of clothes then I felt warm the rest of the night. If you're sleeping on the ground it's better to have a complete seal of a bag vs. potential small gaps between quilt insulation and the pad letting heat out and cold air in. Of course take this advice at your own discretion because I have never used a quilt below 38ish degree. My MH bag has 1/4 zippers on it, thus, it's difficult to vent excess heat so I got the quilt to do just that. I plan to use the quilt in long-run in hammock, but haven't go around to getting a new hammock at this time. As long as weather stays above freezing, i plan to pack the quilt as it keep me warm down to 32 (I probably stay warm a few degrees lower if I pack enough clothes..), and yet I can vent so much heat if weather stays in 40 or even 50s in high elevation in the summer months.It also double as an under quilt for hammock camping. lol. I'm not saying a quilt can't keep you warm below freezing, it could take little creativity to seal off any potential gap above the foot box. (EE's quilt come with foot box that can be zipped. But above the foot box you have to clinch it around the pad to seal it off.)

For hammock camping, if you had under quilt and top quilt, the quilt be AMAZING for 20 degrees-so I would think. I slept in my MH bag in a hammock and it was misery (Again, I got too hot and couldn't vent heat due to 1/4 zippers). You don't have to worry about air gap for heat to escape and air to get in since with both quilts you're basically a human burrito!