The file system permissions need to be the same as if you were using Windows Roaming Profiles...
Check out this MSKB and see if it helps:
http://technet.microsoft.com/en-us/library/cc757013(WS.10).aspx
When I set this up on a NetApp CIFS share (a long time ago) we used the file system permssion set in the above guide and set the network access to "everyone" which worked perfectly for us.
I remember that our NetApp guy made a mistake with the Sytem account and had to use BUILTIN\System to resolve it... it was a while ago so Data OnTap may have already resolved that particular issue in their AD permission handling.
Hope that helps a bit.
PS - I'm sure you already found this, but here is a good KB from vmWare to assist in Persona Management Troubleshooting: