Hi Rob,
I built a test environment with a 2 node 2008R2 cluster and a 2 node 2012R2 cluster with ISCSI disks.
I connected 3 LUN's to the 2008R2 cluster and deployed several VM's from a previously created template with SCVMM 2008 R2. So i had several VM's in my failovercluster manager named SCVMM VM0x Resources.
On the 2012R2 cluster i started the Copy Cluster Roles and imported all the roles from the 2008R2 cluster. I didn't get any errors here. On the 2008R2 cluster i shutdown all the VM's, and took all the CSV's offline. After this was done i disconnected all the ISCSI targets on both 2008R2 servers.
Then i connected all the ISCSI targets on the 2 2012R2 cluster servers, in the failovercluster manager brought all the CSV's online. This all went very well, no problems here.
Then i brought all the VM resources online in the failovercluster manager, that's when the VM's appeared in the HyperV manager again. After this i was able to simply start he VM's again and update the integration tools.
So actually i didn't have any troubles at all moving my (SCVMM) VM's to the new 2012R2 cluster.
I our production environment we will be using FC connections instead of ISCSI, but i don't think this will be making a huge difference.
Guess i am still a bit nervous to use this feature in our production environment, since several people are mentioning troubles with their VM's. Also this migrating feature is a one way operation, you won't be able to go back to the previous situation, when thing do go wrong
-Peter.