I'm trying to work up a backup strategy for some clients, and am leaning towards duplicity for remote backup (already use rdiff-backup for internal/on location backups).

Is it reasonable to want a full backup every so often? Since duplicity increments forward, each incremental backup is relying on the previous increment, and all are relying heavily on the last full backup. Should that become corrupt, bad things happen. A related question: Does Duplicity test the incremental backups for consistency?

Assuming I do want a full backup every so often, how efficiently does duplicity create that full backup? Can/does it check file signatures and copy unchanged data from previous full backups/increments? Basically creating a new 'full' archive transferring new/changed data and merging existing unchanged data?

Right now my concern is that running a full backup is needed, but the consistent large bandwidth use of full backups will make this unreasonable for some clients.