If you've got a working OpenVPN setup, then it probably makes sense to just stick with that. I'm guessing the real gains are only to be had when you want to overhaul your setup anyway.
I haven't bothered setting up wireguard yet, but on paper it looks a lot better and when it's stable I suspect a lot more people will jump on board.
I've sized up its current functionality as useful for replacing OpenVPN, but not yet as a general mesh VPN.
This. I've installed it on Android just because I get a better experience with WiFi switching on when I have a poor signal. And having my SSH connection not break is nice.
This is especially helpful for users with metered connections. You don't have to send ALL your traffic, only the ones destined for LAN will get sent.