I'm happy to inform both packmates.org and yiffit.net users that both sites now benefit from the ZFS filesystem that the new server has been set up with.
I have implemented automated hourly snapshots for 24 hours + daily snapshots for 31 days. In theory they will only grow in size if there's actual changes to the disk of both VMs and I should be able to have enough space.
Furthermore, local snapshots are complemented by the daily offsite backups which allow us to recover even if the full server were to suddenly explode. Full backups are first created on the server itself and then copied offsite so that for a full week we have two independent copies of each day.
Depending on space usage I'll make sure to replicate the offsite repository so that there's two offsite copies for the last 31 days + 7 local copies. That would be 69 individual full backup files + snapshots.