Nice, I guess it does work. Annoying that what feels to me a basic option is hidden for power users. I don't understand what your comment is saying though?

Well that option is hidden because of the very real problems it causes in "normal" syncthing use, as explained on the page.

I'm saying that you can disregard the warning in the case of a backup system (as opposed to the normal use which is full sync between two devices that both modify files).