Amazing and versatile- maybe make a small size?
We have a 20 degree accomplice- have used it about 10 times over the last couple months, in temps between 22 degrees and mid forties. We really love how light and warm it is and would buy it again in a heart beat. I'm a cold sleeper so was just right at 22 with a down hoodie and everything fully cinched- would probably not want to go any lower. My girlfriend is a warm sleeper and finds it easy to vent. We use it with extra wide straps and a dou exped mat. I love that on warm nights we can use it with no straps and be just as comfy.
If I were making this completely perfect for me I would suggest a couple things: 1. Snaps to clip down the flap in the middle when neither sleeper is using the neck snap (we're going to add this ourselves), since it can kind of flop in your face if it's loose. and 2. Make it in a small. My girlfriend and I are both 5'7 women, so we have a little too much material on the bottom and sides. Maybe make a small version for the under 5'10 couples?
Overall, love it!