I used to use Unison. It has a huge flaw. Like rsync, the Unison binary must be installed at both ends of the sync. Unlike rsync, they must be exactly the same

I used to use Unison. It has a huge flaw. Like rsync, the Unison binary must be installed at both ends of the sync. Unlike rsync, they must be exactly the same version, compiled with exactly the same version of various libraries. I was bitten by this so many times, because the path of least resistance is just to install unison from the repo of whatever OS you are using, but if you want to sync between different OSs, may God have mercy on your soul. Sometimes, it works. Sometimes, it explodes. I switched to Syncthing. Your points here are valid, but so far, have not been a problem in the real world.