Hello. You all may find this thread useful. The ENO Doublenest (ENO-D) is comfortable but the hammock material is thin and slippery. The Big Agnes (BA) ReRoutte air mattress, RidgeRest, Ultralight Therma Rest and Speer SPE seems to slide around more in the ENO-D than my Hennessy. Over the course of the night, the BA air mattress slides down and hangs over the edge of the hammock.
So, I salvaged a 17" x 12" piece of ripstop nylon from the homemade hammock sock construction and hemmed the edges. I put the air mattress and Speer SPE in the hammock where I wanted it to stay and at the angle I normally asymmetrically lay at. Then I drew lines around the bottom of the air mattress with a Sharpie and sewed the nylon pocket on to the hammock.
It worked great last night! It kept the air mattress in place and it does not seem to be damaging the hammock's fabric.
The Doublenest's slipperiness was my biggest gripes with the ENO. At night I used to slide down into the sag too much and it was hard to stay flat. That's not a problem anymore. This was pretty easy to and only took about 20 minutes (?) to sew on.