I've been tempted by this set-up too (possibly with the addition of the overcover) - but if something that was fairly adaptable to multiple systems came along I'd (probably) bite the hand off at the shoulder; especially if it could still be used when I have to descend to ground level. I don't ask for much do I?.....I have recently got an 'undercover & underpad' for my HH.....
I use the DD Travel and though I have a 3x2 and a 3x3 DD tarps I mostly use my Hex-fly as it's noticeably lighter.
I also have a home-made insulated hammock/under-blanket but it's too heavy and bulky to use for all but near car camping.
I missed all of the group buys and bought my Wanderinstar under-blanket and quilt from Woodland Edge, they've kept me warm on several trips out already. I love the unrestricted feeling of the quilt though if I were to make one change it would be to increase the width by about 6 inches.
The only thing I'd add to my set-up is a weather-shield, a single layer of DWR fabric to make a shell around my hammock, or at the least to keep the bottom of the underblanket dry as I've noticed it getting a little damp from spray in heavy rain.