"Without trying a Warbonnet, the only observation I can make is that it offers a lot of convenience features which I certainly wouldn't discount, but simply point out that they add weight. Using tension adjusters instead of a taught line hitch and metal carabiners and adjustment buckles definitely speed setup but also add some ounces."
I haven't used both, but both were on my trip this past weekend, and I was the far happier in my Warbonnet Blackbird. PItching was easy for both. Since I'm new to using a hammock, I used the tension adjusters, but I bought both (an extra $15 I think). When I'm used to the correct pitch so that I can pitch it with very little adjustment, I'll swap out the tension adjusters for the line and save a few ounces.
The shelf is a wonderful addition. My shoes go in it, with a few other things, so I don't have to shake them out in the morning, but they're available if I need them in the middle of the night (very rare). With the side entry I can sit and swing on my hammock while I eat, it's a nice 'chair', which I think would be much harder in the Hennessey. And when I zip it closed, it's closed. My buddy's Hennessey actually opened a slight 'hole' during the chilly night, which cooled his butt considerably until he realized what had happened. He hasn't used an underquilt, but I would think that having (and adjusting from the inside) one would be more difficult with the Hennessey (though you're welcome to tell me differently, since I've not seen nor tried it).
I'm thrilled with my Blackbird, I'm a convert after one weekend! I agree with William, the weight is far outweighed by the comfort and campsite flexibility it affords.