I have something simpler than yours, with a small Proxmox server as my NAS (no ZFS) and backups stored to a second disk. Occassionally I will backup the content

I have something simpler than yours, with a small Proxmox server as my NAS (no ZFS) and backups stored to a second disk. Occassionally I will backup the contents of that machine to external drives. In the future I plan on doing something similar to what you have, with a powerful ZFS server and my current server accessing the main server using a read-only interface as a second backup. It does take work to maintain, and I don't look forward to the day when I have a full server failure and need to scramble to replace the unit, restore from backups, and all that. Ideally I would have a pair of servers to handle that eventuality... and down the rabbit hole we go. Ultimately, I guess this all is a tradeoff - I know many engineers who swear on their cloud services, and they simply don't have the time and experience to maintain dedicated servers. While Synology devices and FreeNAS make things simpler, that's for a best-case scenario as you need the technical knowledge to deal with the issues that will eventually pop up. Honestly the cloud is what I recommend for all but the most technical folk, with the addition of external disks off-site for the most critical files.