Hi,
I hate to admit but soon there will be Hyper-V running in our datacenter along with VMware :-) . We're going through the design sessions right now and one point that came to table was the discussion on wether we should mix Hyper-V and VMware hosts on the same array. The only thing I could come up with to NOT mix them is that an upgrade of ESXi may require a VNX flare / blockOE version that is not yet supported by the Hyper-V hosts. But I'm not sure if this is enough to justify buying a separate array just for Hyper-V.
Are there any other concerns? LUNs of course will not be shared, but could I share storage pools? Would mixing loads make troubleshooting more difficult?