An alternative is to try a wider pad. The Oware I use is 40" wide...in the hammock it tends to cup around the shoulders providing extra insulation and wind block. And, mostly because of its 40X60" size, it doesn't slip in the hammock. But beware...wider pads make for bulkier packing.
The sagging issue might be the new fabric/lines stretching out. If so, that will go away after a couple uses. Otherwise, make sure your feet are on one side of the centerline and your head and shoulders are on the other side. The distribution of your body weight may be a factor too. Raise the appropriate end of the straps to accomodate the difference.
My HH is about four years old...I can't comment on the quality of today's HH.