Hey Stage Coach,
I had this kind of situation. But here is my scenario. I have to upgrade the vcenter & hosts from 4.1 to 5.X and move the vm under the newly build vcenter 5.X. While moving the vm's under the new vcenter we have to change the name of the vm as per the application in it. So i have made both the vcenters in linked mode where the vcops recognized it and it started collecting data for the new vm's and old vm's. As soon as each vm is being moved in to the new vcenter (by cloning) we are decomisisoning the old and vcops is also not recognizing the old ones. the only problem with this kind fo method is u have to rename the vm and the vcops should have a license key which can hold double the size of your vm environment so that when u do linked mode it wont stop collecting metrics due to the license issues.
Thanks
VK