After upgrading to v8 the following issues are observed with the existing jobs processing Hyper-V VMs with SCSI disks:
First backup job run will transfer entire VM disks into the incremental backup storage. The following job runs will operate normally - regular incremental restore points will be created.
First replication job run will create and attach the new, duplicate SCSI disk. After that, entire VM disk contents will be replicated to the newly attached disk. As a result, replica VM will start consuming 2x space on the target storage.