I didn't get to it until fairly late in the day, so I can only give initial impressions. In the next couple of days, I'll try to rope in a friend to lie in it so I can see it from the outside.
Initial impressions: it seems to fit the DoubleNest fine, lengthwise. The trick with using the whoopie sling tails to hold the small d-rings at either end works fine, but I may play around with shock cord prusiks or something similar--I don't like having to undo the bug net if I need to make a quick adjustment to the suspension.
All in all, it felt pretty roomy...but it felt a lot closer to me on the underside than the ENO bugnet I had before. I could put clothing, boots, whatever on the ground INSIDE the ENO and still have it inside the bugnet, for easy access. I don't think the WB net will interfere with an underquilt or anything, but I did notice it being a bit closer to me as I entered and exited. Inside and relaxing though, it was plenty of room for me. I'm not an overly large guy, though--6'1" and 190lbs.
Now, the pluses--the view inside was SO much better than the ENO net. I don't know what the difference in netting is, but I felt isolated in the ENO, and still a part of things in the WBBN. The material also passed air better, so I could enjoy the breeze as I gently swayed to and fro. The horizontal zipper gave me much freer entrance and egress (although I will have to get used to how to best hold the loose fabric so I can get it zipped up when fully open).
So, I like it. I may eventually regret spending the money instead of just saving up another $100 for a WBBB with the integrated net. Still, it never hurts to have a backup setup for if I want to include a friend in my travels...!
And for now it will suit me JUST fine.