Cool stuff!! Let's see how long they and the strap will last.
I have 3 pairs of metal straplocks. On a heavy guitar they wear out, but there's no way without them.
And if the guitar is about 3 kg or less, I like it without straplocks.
This saves weight and less metal ringing. Although straplocks can be lubricated with graphite.
These rubber bands are better than straplocks. The main thing is a hard end of the strap, a wide mount like on Ibanez (Preimium or Prestige) and these rubber bands on top.