After experimenting with Hennessy and homemade hammocks, and Jacks R Better quilts, I would also offer up the following: The Exped Ergo Combi. I don't think I'll be dropping that kind of cash anytime soon, but it has a few big draws in my mind.
1) No underquilts. They're a finicky pain in the rear, IMO--to get them adusted just right so you have a tight weld to the hammock to block out drafts, but not so tight you're compressing the insulation. The Exped uses your Downmat 9LW in a special sleeve for bottom insulation and since it's an air mattress, it's a lot harder to compress than a down quilt (I ought to get a check from these guys as much as I stump for the downmat). I'm a firm believer in the downmat, have to believe it would work well in this application as well.
2) The hammock is built on the diagonal. A lot of hammocks, like the Hennessy & Warbonnet are built to allow you to lay on the diagonal and relatively flat. The Exped is built on the diagonal and uses your pad to stretch it out--you can only lay on it diagonally.
3) Comes with a massive tarp that can be pitched like a Warbonnet SuperFly to block blowing rain/snow etc
4) Removable bug net. Nice to have when there are bugs, nice to leave the weight at home in the winter.
5) The attachment system seems to incorporate a lot of innovations in the hammock "industry". The hammock goes up easy and a drip guard is incorporated. A little sleeve over all the suspension cords keeps them from getting all tangled up, and the tarp clips into the hammock suspension, seems to be pretty easy to center over the hammock and get tight.
When I watched the videos on their site I just kept seeing one little feature after another that looked refined--like they would eliminate or reduce all the little aggravations that come with a hammock in cold/nasty weather. When the low temps are in the 70's and the skies are clear, a little sliver of closed cell foam and a bug net are about all you need to be comfortable. When the temps drop and the weather gets nasty, all the little details become a lot more important.
In the reviews on REI, though, I saw at least one or two folks complaining that you had to be average height at most to use it. That doesn't make a ton of sense to me since it uses the 9 LW pad, which I fit on just fine at 6' 5", but I did read that FWIW.