I just have to say that I'm another happy SuperShelter user. I've gone down amazingly comfortable to the low 30 s using a 30deg sleeping bag, cotton boxers, poly shirt, the undercover, ocf underpad and amk heatsheet. The SS does have some details that can be a pain at first, but its really nothing that a few mods can't solve. After solving these probs, using the hennessy with the supershelter becomes really cool.
A 2Q zipper mod would definitely make it easier to adjust the pad while in the hammock and easier for people who don't really like the bottom entry but do like the hennessy lay.
Also, the instructions on the SS stuff sack are very clear in my opinion but they could stress a bit more the importance of putting the hammock guyouts as horizontal as possible, at least the head end (left guyout); this for me improved comfort a lot and underpad coverage seemed better.
I came to realize (kind of an obvious thing) that the level of comfort and proper placement of the underpad depended on how I entered the hammock. Best way i have found to get into the hammock is to try and not move or push the pad aside but to fold it instead, then keep it folded on my right hand as well as the hammocks' entrance slit. Once im in i stick my hand out the slit to unfold the underpad. Note that the pad won't completely fold but does allow you to enter the hammock and will stay more to the left side solving the upper left side coverage issue.
No matter what i did, the pad just didn't work on the feet section: always to much to the left. Sticking the right guyout far away and horizontal does help a bit, but to completely solve this i recently had to attach small loops to the hammocks' edge and the underpad and by using a small clip or minibiner I attach the pad to the edge of the hammock. I got into the hammock and I had my girlfriend help me out from the outside to see where the attachment loops should be on the hammock and the pad.
Other from this I've found it more comfortable to hang the feet end of the hammock just a little bit higher than the head. I didn't hang the feet end to much higher than the head, but I had to reduce by more than half to get comfy.
Hope this helps out. Any tips are also welcome.