Should I configure both NFS and CIFS access to the NFS datastore volumes on the filer to make it easy for Windows based administrators to edit .vmx files, etc? Just NFS access does make export security admin simple which I think is probably the best solution.
I have a hidden admin CIFS Share configured for the underlying volume, with the CIFS permissions locked down to a user or one group on the appliance.
We dont use SMVI currently, but have snaps enabled at the volume level, so if we really wished to restore a previous version of a VM, we can using the previous versions tab, within the CIFS Share properties. This is just an easier method that entering the details at the CLI.
If you really want to lock it down, then no. I also agree, I wouldnt reccommend editing the VMX files directly.
One (slightly border) case when simultaneous NFS & CIFS access is priceless: a datastore for iso images.
Providing you use some Windows management station, you can download an iso directly to a CIFS share &, if the same volume is presented via NFS to ESX hosts, you can mount this iso straight away to your VM
(and yes, security is a concern - but it's so simple to use! )