Sorry to see that what I predicted about the apparent lack of appreciation for what this piece of equipment can do to improve photos has come to fruition.
In some cases, the current availability of cheaper gear, sometimes with more capabilities than the 'old stuff' renders demand near zero for the older stuff (AA battery pack vs. Quantum packs, as one example)
HSS-compatible radio transmitter/receivers made in China vs. Cybersync transmitter/receiver without flash remote control is another.
I cannot figure out what made the utility of Custom Bracket and other flash brackets disappear!
I used my Newton bracket with medium format film SLR 30 years ago, but I can still use that same bracket (and have done so) with a Canon dSLR, and the benefits remain unchanged.