Are they using oVirt? I know other types of KVM versions are sometimes field certified... This would be for VM-level protection, right? I'd imagine SLES could be the sticking point here, as I don't know if the VSA is certified on it.

Virtual Server Agent Support for oVirt on KVM

We can only backup VMs running on KVM via oVirt as @wgrande implied. I dont think SLES would be an issue since the VSA needs to be installed in a guest VM, which could be RHEL or any other supported flavor of linux for the virtual server agent. But you could still backup the SLES guests without issues.

However, that caveat of oVirt still exists - KVM does not have the required APIs to perform robust enterprise grade backups by itself without the oVirt management layer on top.