Rich,
I have used the system now for a good number of climbs. In the middle of it all I received a New Tribe Pro-Gear saddle, with central anchor point, as it was cumbersome using the old buttstrap and having to connect and disconnect from two D rings every time I had a redirect. The system works well. My arms may not be as long as I thought, as the hitch (Vt) is practically out of reach when in extended mode (about two inches less might make a difference). When pulling down to ascend, the slack girth hitch 'relaxes' and opens a bit. Maybe I don't have it set up optimally. I seem to have to 'tend' the hitches a bit now and then. My Vt was problematic early on until i found a combination of length/wraps/braids that worked well with my weight and ropes.
I really like the system, and have used it exclusively for tree entry for trimming, especially enjoy it on the long hip thrust entries. It's a far sight better than the old tautline. I have not even reached for it for takedowns, as I keep things close and minimal while spiking.
I am interested in your updated design. Pictures?