That is my understanding but I am also a ground dweller. There are forums dedicated to hammocks, but it seems most people end up choosing them for comfort (and having no or little weight penalty).

In terms of backside insulation. I have heard of people taking their normal air mat in case they are forced to sleep on the ground. I once read a review by Phat (a moderator we haven't seen in awhile). I think he had a piece of fabric under the quilt with a large air gap that he filled with dead leaves and duff. From what I have read, the most popular choice appears to be an under quilt.