Please do not use my bad experience stop you!
Longhorn is a nice tool and as you can read online and in other posts it works very well. I may have unlucky, have a bad configuration or had my PIs under too much pressure. Who knows! My advice is try something new: k3s, longhorn, etc. That is what I use the PIs for. I would not use Longhorn at work :D
I’m really not sure what I even want the distributed FS for. I guess I wanted to have redundancy on the pod long term storage, but I have other ways to achieve that.
I am not using replicas :) I use longhorn for the clean/integrated backup mechanism instead of using something external. Maybe one day when I have the same-ish disk speed on all 3 PIs I will enable replicas but for now I am good like this.
For backups of important stuff maybe use something else or ALSO something else. I was personally thinking to use another backup too for longhorn devices like https://github.com/backube/volsync or velero to have a secondary source in case something happen.
Also longhorn is always getting better. This is just out of the press https://github.com/longhorn/longhorn/releases/tag/v1.5.0
My advice? Try it out! If not, it will still be a source of learning and fun (but I am strange, I like to debug stuff).