Don't know how the ghost itself will work out, but after spending time in the ambush and playing with an old assassin harness, there is definitely merit to the idea, and I'll be building something similar.
To me, if you're standing on a large platform (and that has its merits) it makes more sense to use something like what Kuhnert has. The design just needs refinement. I have a few ideas I'm working on, but I think it would be very easy to take the riggers belt design and bring it up-to-speed with today's stuff.
I've killed a good amount of deer the past couple of years from a ROS and a sling-style saddle. It's quite doable but the bridge is absolutely in the way, especially for a weak-side shot. Saying it isn't to me is like listening to a guy say his assault and 4 lone wolf sticks arent heavy. Ok. Take this roll of carbon bolts and this saddle and get back with me. Maybe it doesn't impede everybody's results, but it's still a thing. For most of us it's just a thing we've figured out.
A belly button high hookup point means there's as little in the range of your bow and bow arm as their can possibly be. That's not comfortable or feasible from a ROS or if you sit, but it absolutely is if you're leaning on a big platform. I spent 4 or 5 all day leans on an ambush, and by the end of it I was quite comfy with my tether as low as it would go. My buckle on my tether is usually touching the tree, and most of my weight goes into the top 2" webbing on the kite.
A riggers belt style harness makes that hookup much more comfortable. It sits right at your waist most of the time, and actually provides a little back support. I don't personally need that, but it would be the cat's azz for those who currently carry separate back bands. When your ready to sit for a while, just slide it down under your butt and sit.
Same day LWCG did that ghost video they also did this much longer one. It's mainly about the evolution of the Kuhnert-style platform, but they go over the harness as well. Wish there was a way to edit out everything but Kuhnert talking, since both of the D'acquistos and whoever the other guy is add little to the discussion, but it's definitely worth watching.
I think the whole system makes a tremendous amount of sense. I never understood the leaner/platform crowd until I started doing it Kuhnert's way. Kinda how I struggled to get dialed in on a sling and a ROS until I started really looking at how Eberhart did it. Two different systems. To me it doesn't make sense to marry a sling to a platform, or a riggers harness to a ROS.