I do not have any details on the exact cause of the issue at this point, but I recently did an OCS 2007 R2 deployment on Server 2008 R2. We followed the general instructions located on TechNet to install the OCS services on 2008 R2, but ran into an issue when performing user moves from LCS to OCS.
Not a lot of information in the errors, but pointed to a connectivity issue between the LCS server and the new OCS server.
The fix for this issue is to install the admin tools on a 2003 Server, once the admin tools were installed on a 2003 sever in the environment, the moves were successful. I am working on finding the exact cause, but I am betting it is related to the bullet item for admin tool compatibility issues listed on the 2008 R2 support page. Will update when I have more information.