About two or three weeks ago I moved from BTSync to Syncthing, because the former has gotten first worse at inter-OS synchonisation (I’ve found no way to keep my Linux server and Windows desktop in sync) and UI. With version 2 and it’s changed sharing system and share limit of 10 I decided that enough was enough. A solid bonus for Syncthing is that it is open source too.
Experience so far is quite solid: sync across 3 systems (win and lin) is flawless. I had one issue where I converted an old share by adding the same folder (on two machines) to the same share at once. That caused Syncthing to overwrite every other file. Not sure why, but having 1 machine seed the shared folder is reliable, if a bit time/bandwidth consuming. Since Syncthing polls for changes as opposed to some inotify-based system, I reduced the polling interval to 5 minutes for each share to prevent it from battering my hard drives. Also CPU usage is a bit higher, especially if there are many changes. Fortunately those peaks are usually pretty brief for me. Other than that performance is great; it saturates my LAN. My biggest worry was firewall holepunching, but that also seems to work fine; I reliably can connect from work without configuring anything.
So far, apart from a slightly more involved setup, an improvement.