The increasing demand for Hyper-V and more and more geographically distributed storage systems put a limit to the extension of HP's 3PAR StoreServe storage family. MetroClusters are only supported for VMware environments but still lacking the support for Hyper-V or other clusters based on Microsofts server operating system.
This limitation will only exist for a few more days or weeks as HP announced support for PeerPersistence for Hyper-V for the 3PAR systems. Currently the exact release date is not published officially but will be soon.
So if you wait for this functionality, don't wait any (much) longer.