Hi Jeff,
I'm just finishing up my review of the Hennessy Hyperlight and it is EXCELLENT. That's a great choice.
As far as insulation, here's my take:
I like the Hennessy Supershelter but I got cold below about 40 deg. However, I'm a cold sleeper.
I've also been testing the Jacks 'R' Better 4 season system and it is GREAT stuff. For three season use, I like the Nest underneath and a No Sniveller above. The Shenandoah with another top quilt would be a great deal as well.
The JRB Weather bottom is a great idea for when the winds pick up- winds can really strip the warmth away from a hammock so pick your sites wisely.
I've also used the Gossamer Gear hammock pad. I agree with Douglas that it can be hard to position these. However, I've found that this pad gives excellent warmth for the weight and is a fantastic choice to give your hammock system a boost in colder temps.
You will love the JRB/Hennessy combo. These are truly the most comfortable nights I've ever spent in the backcountry. The easiest nights have been above/below hammocks- getting situated in a hammock is a little tricky and I wouldn't want to use a pad every time if I could avoid it.
Best of luck with your hammocking! I'm pretty new to this too and it sure is a great way to go!
Doug