Of course if i send HDD, there will be a copy of the NODE (in rsync option) and i only rsync changes.
But as i had this experience in the topic bellow, where i counted up to 200Mb/s write to new HDD, but in reality i’ve got only 25MB/s (because of milions tiny files), i believe that 12mb/s is also just very theoretical math, but reality can be 2Mb/s or so 