Migrating from DS1511+ to DS1520+

I have bought the Synology DS1520+ and have to migrate from the current DS1511+ to it. As I have said in the blog post, I wanted to make sure the migration was seamless and hence I deliberately chosen a similar model (just more powerful as it is newer). Indeed the process was so smooth I nearly dropped from the chair. I recalled a similarly smooth process when I took out 4 hard disks from my DS1511+ previously to add as a volume to the DS1813+. But that was to create add a volume from a NAS to another NAS. This