Unfortunately I've found it rather buggy (on linux) in the past. It really could be a super nice tool, if they traded some features for more stability, in my opinion.
This is also my experience with JabRef on macOS. If I remember correctly, I had some problems where it silently corrupted parts of my bibliography. I'm not sure if it was related to me using it with subversion or some other problem, but I was a little bit surprised to say the least.
Ouch, that sounds pretty bad... Thankfully I didn't have that issue - mostly my problems were to do with java libraries, glitchy UI, and the "add reference" tool often didn't work.