Do you still have to initialize any disks you add, forcing you to wipe the partitions off of them, if you want to use them with this NAS? The last version of ADM I tested (about half a year ago) still forced this, and it's the reason why I consider Asustor a horrible choice for a NAS. You can't just pop in your existing disks and share them instantly.
Hell, you have to reinitialize (and lose the partitions) even if the disks were previously used in the same NAS. So pressing the reset button on the back is enough to destroy everything you store on the device. That's pretty damn critical if you ask me.
The up side is that they use some basic linux system internally with mdadm for raid, so it's possible to restore the data even from under Windows.