The vaults feature was forgotten when Aperture 3 allowed for multiple libraries. Going through all your libraries and updating a vault for each one is tedious. Also, a backup isn't a backup if it's in the same physical location as the computer. If the computer goes (theft, fire, water) then it's likely so will the vault.
I have a backup in my bank safety deposit box. That's what saved me. My backup scheme worked but I have to be more frequent with my backups and go to the bank more often.
IMO your backup kind of failed as you lost a months work!
With Aperture you should only need to split into multiple libraries if you have a
lot of photo's, meaning >tens of thousands. Aperture is designed to handle it, that's its purpose.
Vaults still work when you have multiple libraries, update the vault after using it, before switching to another library, not really that tedious, and quicker than making a copy of the whole library.
Our workflow has vaults and referenced masters backed up on a local external drive that is swapped with an offsite drive. We also back the library and masters up with time machine to a time capsule, so we have two local backups that are up to date within an hour, and one offsite that is never more than a week old, more frequent if a lot of important work has been done.
In your case either of the local backups would have saved you, the offsite really needs to be for disaster recovery!!
CF/SD cards aren't really backup, too easy to accidentally format them!! Copy them to another location on or before import to Aperture. We use the facility within Aperture to copy from the CF to (yet another!) external drive as the files are imported. If you are really concerned, copy them using finder before import to Aperture to prevent any chance of Aperture corrupting them.