SharePoint Backup and Restore: Same amount of free space required for initiating full or incremental backups

Just observed that during initiation of SharePoint Disater Recovery Backups (via STSADM or Central Admin), it expects the same amount of free space to be available on the UNC path irrespective of whether you are taking a full or incremental backups. This turns out to be an issue for large farm scenarios ( data > 500 GB) as after having taken a "full" backup, the free space available on the share might not be greater than 50%. The operation will not start if the UNC path doesn't have enough free space which it computes in the very beginning.