I'm adding to @planedrop, this feature is awesome!
This is the first time I see using all NIC transfer features, both ends of the NFS tags are on two QNAP SATA RAID 5 disks (not SSD) connected at 1Gb/s and the transfer was steady at 104MB/s .
I used the function to synchronize the two QNAPs, so on the first boot I used one NFS(A)->NFS(B) job and then a second NFS(B)->NFS(A) job and now I am perfectly synchronized, without concerns which snapshot the bacukps are from.
I stopped backing up VMs to two NFS targets simultaneously, this new feature is more performant.
If possible, in future versions it wouldn't be a bad idea to see the progress of the copy inside the TASKS !
Thanks for the great job!