My assesment so far after 12-15 sessions in the woods experimenting with different climbing methods and such; (on at least one of the days everything was wet, so it got the water treatment too): I'm sticking with the Nutterbuster kit. I went back to the rope tether for a few sessoins (with klemheist friction knot). Tried my old favorite treestand harness tether too, which is very seat-belt-like and has a fantastic buckle. In the end the Nutter buster kit won for its weight/size advantage. Also, I seemed to me that when girth hitched to the tree, the 1" tubular, even though it was quite floppy, "wanted" to stay put more than the other tether materials.
The only down-side (which is minor) is that the webbing wants to twist a bit sometimes as it enters the buckle
FWIW, I had a short section of thicker, stiffer webbing of unknown material (nylon? polypro?, polyester?) that came from an old treestand harness package. I don't remeber its purpose, but I think it has something to do with self-rescue, like a runner or something. Anyway, I found that the "twist" issue was resolved with that, it fed into the buckle very well. Unfortuantely, I couldn't expeiment much with it to see if it had negative ieffect a tyether material because it was too short. In due time I may see if I can identify the right stuff (stiffer, strong 1" web) and give it a workout; but for now I'm content.
Many thanks to Nutterbuster