It's really going to depend on your requirements, but there are some definitely disadvantages of bare metal backup vs something like JetBackup.
The advantage of a bare metal backup you're going to be 100% assured that the server is exactly the way that it was when the backup was take. The major disadvantage if a bare metal backups is that you have nothing until the restore is 100% complete. Depending on what software you are using and how much data there is to restore, that process can take a really long time. The other disadvantage is that if there is any glitch in the restore (because stuff happens), you have to totally start over.
If you have a well documented cPanel build/install process, you can, more than likely, get the OS, cPanel installed and configured in an hour or so. You can then start your DR recovery with JetBackup. The advantage here is that as soon as an account finishes restore it's up and live. Another advantage is you can change the priority of the different account restores so you "important" (or screaming) customers can be restored first. The disadvantage of JetBackup is that you need to be a lot more organized, have well documented build procedures (so you can build cPanel servers exactly the same each time). You're also going to have to make sure that you have all the files/folders backed up that you need. As an example, you'll want to make sure your backing up the Apache config file. You won't want to restore that, but if a site with a dedicated IP gets restored, it may not get the same IP and you may want to put it back to where it was to not cause a lot of DNS issues.
It's definitely a trade-off between bare metal vs. account backups, but either can be very effective with proper planning and documentation.
