Neither of the two ESX hosts would have anything to do with one another (except the physical connection to the FA) and would be unaware of each other and therefore would have zero impact.
I have ESXi5.5 using powerpath connecting to a VNX 5500.   My question is is there any ramifications of connecting esxi5.0 using the vmware native multipathing on the same array.  The two version of VMWARE would be in different storage pools and different storage groups.  But, they would be using the same SP ports on the array.  My thinking is the answer is "no, there should be any gotcha's".
VMWare versions and Powerpath questions