To answer two questions at once:
Why not use some QR buckles instead, perhaps ones that could be compatible with these?
What about the QD's from the Luma Loop? I thought those looked pretty slick.
Our previous Loop Mk I and Mk II were both single point slings, so only one attachment point was required. At the heart of the Cinch's function is the fact that it is a two point strap. We found one dangling bit hanging off the camera an acceptable tradeoff for the Loops, but two dangly bits gets super annoying very quickly.
So our goal with the Cinch QD solution is to create something that requires minimal junk hanging off of the camera, and the parts that *do* connect to the camera need to be as minimalist as possible.
This drew us to gate hooks, carabiners and the Le Hook - we have a custom designed triangular split key (like a better version of what Nikon uses) that can go on lugs and Canon brackets. The gate hook just clips right into it. On the tripod, we have an injection molded carbon fiber ARCA plate with an integrated membrane connector, providing a flexible D-ring to one side (hey; if we are gonna put something on the bottom of your camera, why not add some value and build in a small ARCA dovetail?).
Turns out, the connection infrastructure was far more difficult to design than the gate hook (finding someone to make a crazy triangular split key was a massive challenge, as was someone who had the skill to make the injection molded carbon plate). Now that we have those parts complete, circling back to the actual connector component is not such a huge challenge.
Market research question: What do people think about screw lock quick links?
They aren't super sophisticated, but we find the absolute reliability of those components to be a very compelling featue.