I worked at a place with its own colo where they ran several multi TB MySQL database servers. We did weekly backups and it could take days. Our backups were stored on external USB disks. The I/O performance was abysmal. Taking a filesystem snapshot and copying it to USB could take days. The disks would occasionally lock up and someone would have to power cycle them. Total clown show.

I would rather pay for RDS. Databases are the one thing you don't want to screw up.