I was able to get a good idea of what my 3s Yeti can do. I had 34-35 degrees, a 10(?) mph gusting wind, and I never felt chilled. I was using my OES Dlx, #3 (32degree) Montbell SS, a fleece pullover and sit pad under my legs.
The wind shifted a little and blew through my tarp like a tunnel. Other than my bad setup,everything went well. The Yeti held perfectly on the hammock ends without any biners or extras.
The Yeti slipped sideways when I went on a bathroom break, but that was an easy fix.
I am working on an add-on, using insultex, to boost the low end temps, but I think 30 is a conservative estimate for this guy. This setup has allowedme to cut 20 oz from my pack.