As far as have seen. Root access is crucial in some cases. I've met problem on vSphere 5.x (Ess+) that without root access sometimes datastore keeps meta information of accessing hosts through takeover-giveback process so NFS share become RO. (File level RO, so i was able to create files and directories through datastore browser but as unable to write even one byte to files, without difference, newly created or existed before.)
After giving root access to share for hosts of ESX cluster - operation returned to normal.
So better give root access for ESX hosts, and better to write it in stone (/etc/exports).
And for sure - SAN network for vSphere cluster must be isolated VLAN, in optimal - unaccessible physically from outer networks. (Nothing for BlackBerry mr. Stetson - just healthy level of paranoia)
Regards, Ivan Ryabtsev (NCDA)