Personally, I have my sites backup on my home NAS once a week. It really wasn't that difficult to set up using DirectAdmin. The tough part was getting my router all set up and forwarding the FTP to my NAS.
It works really great. Once a week, my router reboots and refreshes my dynamic DNS. Then, there is a job on my DA account that pushes backups of all accounts to the FTP server.
The best thing really is to have backups stored off-site meaning out of knownhost's network so if there was a network failure you would still have access to data. If anyone wants a recommendation for an excellent backup company feel free to PM me.
Even so, KH offering a backup solution would be a nice add-on.