I thought I'd try a newer version for speed as PT 4 has a few slowdowns on macOS.

However, currently, going with a version greater than 9.3 will cause you a few issues: HUD not appearing normally, HUD nor working, both in games and replay.

Secondly, when you revert back to an older version, you may run into Restore issues.

Best to wait until PT actually announces support for newer Postgresql versions to attempt an upgrade. In that case, ensure you have a good backup stored safely somewhere.