I have been using Syncthing for some time and it has been excellent. The only downside is it actively tries to establish P2P connection when I have a central server with a public IP. Other than that it's great.
I kinda disagree. Sure, having a nemesis will drive up your wish to learn more stuffs & outperform him, but at the end of the day, you must hate each other's guts to become each other's nemesis. Which is very unhealthy if you are needed to work in the same working environment, since each of you'll have to deal with the other one all day long.