Not long ago, i've talked about QSM. If you've missed it, please refer to http://www.ms4u.info/2010/01/quick-storage-migration-via-vmm.html
Recently i have use QSM again, let me share some experience which i've encountered when using QSM.
Q. Can i use QSM on online and offline Virtual Machine?
A. Yes. You will experience interruption when the Virtual Machine is online. This happen, when VMM create a snapshot.
Q.Can i use QSM to migrate from a standalone Hyper V to Cluster Hyper V host?
A. Yes. VMM allow you to move VM to Cluster Hyper V host. Make sure VM Configuration and Virtual Hard Disk is point to Clustered Shared Volume. Once it move to Clustered Hyper V host , VMM will make the VM as High Available Virtual Machine (HAVM).
Q. Is iso files bind to VM move as well?
A. Yes. Make sure you unbind any iso file. This including vmguest.iso (Integration Services) after use.
Q. Will QSM move differencing disk and master image?
A. Yes. This is dangerous. QSM will not make a copy of master image. It will move both virtual hard disk. You will not be able to start other VM which is using the same master image. I advise you to use Export/Import feature to avoid problem later.
Stay Tuned and feel free to add comment regarding QSM experience that you have encountered...