The great advantage of having it separate is that it will be available if your T610 dies. And anyway, there's nothing inherently wrong with internal storage. Using a dedicated disk array will likely give more bays of course, but with 2TB disks so cheap that is unlikely to be a problem.
FWIW, my own solution uses an old 6-bay PowerEdge loaded with 2TB SATA drives (WD RE4s) running in RAID-10 on a Perc-6i (with 256MB BBWC, not the useless 6i/r). That's backing up over a dedicated VLAN 50+ VMs daily and chugging through the transforms at the weekend - works perfectly for me