The stats from moving a 4.4TB storagenode from Windows PC to DS220+ NAS, with robocopy:
(the speed is aprox 1TB/day)
robocopy /MIR "X:\Storj" "\\NAS\Storj\storage"
I saw somewhere in docs that after 12 days offline the node is suspended and after 30 days it is disqualified. So you should be good when moving with robocopy max. 10TB storagenode data. Above this, you should use the rsync method or something similar.