We're currently (finally...) making a switch from EMC to NetApp, and our brand new Boxes are running on ONTAP 9 
but we have a weird problem, currently blocking our cifs migration...
when using a cifs share on a svm hosted on one of our new FAS 2554 (which were delivered with ontap 8.3 and upgraded to 9 before any configuration) we cannot set the owner of a file or folder to any other user.
I can surely TAKE ownership of a file with my admin account, but I cannot set owner to some other user account... something we require for the migration of our terminal server profiles.
oddly enough, when creating a cifs svm and shares on our - also new - AFF 8040, which was delivered preinstalled with ontap 9, everything works fine.
our netapp consultant also was kind of clueless about that and couldn't reproduce this issue in his testlab, so we opened a case.
but maybe someone of the community knows what's going on
either way, I'll post the solution once the case is closed.
as for the exact error message that occurs when trying to set file/folder owner on a FAS 2554 cifs share:
The security ID may not be assigned as the owner of this object