Absolutely top! I always recommend syncthing. I use it to sync and backup data in different situations which are all similar to what others reported here.
One thing I'd like to add is, that syncthing is also configurable in detail. I use it to sync data between a workstation behind restricted network and my laptops (most of $HOME). For this I use ssh-tunnels between the hosts. So syncthing's public discovery would not be necessary. I can directly set the tcp endpoints for syncthing so it find its communictation partners. Nice!
Anyone here who decided to try to sync files at TB scale?
And what about file holes? AFAIK syncthing filles them with zeros. Is this still the case?