Just FYI, the immediate issue that led me to seek a server replacement was a lack of backups for the data. I host stuff for other people, and although in theory they should be backing up their own stuff, the reality is that they probably aren’t.
My initial survey of my storage situation led me to believe that I didn’t have adequate resources to back things up, but I started digging deeper and found several gigabytes of useless data I could delete. I have now set up a backup solution that ensures only one day’s worth of data is lost in the event of a problem.
There are still some improvements that I want to make to the system to enable direct snapshots, but to do it I will have to completely rebuild all the filesystems. To do this without downtime means I need another server, so if someone happens across an awesome deal, let me know.