If you are not using RAID or JBOD, you should be able to transfer disks from one unit to another and still have access to your data - based on what D-Link have told me, the disk configuration is stored on the disks, and so you can theoretically transfer the disks from one unit to another, with any configuration and still get access, but I have not tested this personally.
Based on the wording of the subject and the post - I would guess that your interest here is in "disaster planning", so, I'll also add - you can also get access to the data from separate disks and RAID1 by installing the disk in a Windows system and using the ext2ifs installable file system driver - I have tested this with Windows XP, but not with Vista.