Wow!
For what it's worth, here's some thoughts.
The gas-patch items look great but I would ask myself, how strong are they? can I drill a hole at the correct angle and how do I attach a "wire" to the eye and trim off the excess to get a neat job. If you don't get a dead straight run from the upper wing to the lower wing, it would look horrible. What would I do if one of the turnbuckles broke off flush with the wing?
I'd have the same problem with the home-made items, cutting off the loose end, assuming you would be using a monofilament.
I think I would plump for the AA stuff. Using monofilament you'd get a nice straight run and trim the ends beneath the wing where it is less visible. It would be a simple job to slip the tube over the "wire" before installing the lower end and you can slide it into position later. You could colour the brass with blacking agent and your not relying on the turnbuckle for any strength.
Just my thoughts.
Haddock.
Your post arrived while I was typing mine!