Comfort in a hammock has a number of aspects.
One is the "flatness" of the lay. This depends on how severe the diagonal you can lay on is. In the extreme you might lay 90 degrees w.r.t. to the suspension lines, and (depending on the width of the hammock) be as flat as possible. This is what Mayan hammocks do for you. TeeDee has pointed out several times that this essentially is what a bridge hammock does, by putting the suspension at your sides rather than your head and foot. I haven't tried (yet) but the ENO double is 6'8" and might actually work this way.
So I digress, but not really. The point is that in an ENO double you can hang with the same diagonal angle as in a BB, and essentially the hammock beneath you is as flat as in a BB. In this single aspect of comfort I think it is a wash between them.
But comfort is not just the lay. Comfort includes your perception of your interior hammock environment. The shape of an ENO double is a honking great rectangle. IN PARTICULAR, when you hang at a sharp diagonal your feet and head are not in any kind of danger of falling off the hammock. There is fabric beyond both head and feet. This means that in order for the hammock to be wide enough so that you can lay at a sharp diagonal without feeling like you're about to fall out, you get all kinds of fabric above you in places you don't need it. People that comment on the flappiness of the ENO double hammock are referring to that.
Brandon's insight is to have the "base" rectangle narrower than you would have with an ENO double. If it didn't have the extra fabric panels, then when you'd lay at the same diagonal angle your feet and head would seem to be in danger of popping off the hammock---you're at as sharp an angle as you can be without spilling out. But he put the extra panels in to give you more fabric---and keep you from falling out---at only the places where you really need it. And then, to keep that all from flopping in on you, the side pull-outs pull it all away from your body. In this dimension the BB is clearly different from an ENO double.
The shelf is a brilliant touch made possible by the extra panels.
That's my take on it anyway, and I'm sticking to it!