In the last weeks qmpbackup has seen a bit more improvements.

• Adds support for CEPH/RBD backed devices.
• Allows to use unique bitmaps for having multiple, separate backup chains.
• Adds support for jsonified filename configurations like often used on proxmox systems.
• Adds support for saving attached pflash/nvram devices (storing UEFI related settings)
• qmprestore can now merge the backup chain into a new image file and the new snapshotrebase command can rebase the images and after committing, creates an internal qcow snapshot, so one can easily switch between different vm states in the backup.

Ive been running it lately to backup Virtual machines on proxmox systems, where the proxmox backup server is not an option.