I’ve been using the fdroid syncthing-fork version for a long time now and haven’t had any issues at all… Doesn’t mean it’ll last forever but it’s been getting the job done for me even in its current state.
… And can’t remember my original reason to use the fork instead lol
Raid 1 has saved my server a couple of times over from disaster. I make weekly cold backups, but I didn’t have to worry about it when my alert came in notifying me which drive went dead - just swap, rebuild, move along. So yeah I’d say it’s definitely worth it. Just don’t treat raid as a backup solution - and yes, continue to use an external cold storage backup solution as you mentioned. Fires, exploding power supplies, ransomware, etc don’t care if you’re using raid or not.