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I do not have personal experience, but I can't see why it should be a problem. EPiServer supports 64 bit, and Hyper-V is a good virtual technology, so there shouldn't be any problems. (As long as the host server running good enough hardware)
Example: (not EPiServer, but Hyper-V related) Microsoft are running microsoft.com and all their databases on Hyper-V...
I can confirm that. We are doing all of our development on Hyper-V virtual machines running Windows Server 2008 and 2008 R2 64bit without any problems.