As a follow up, export policy rule limits have been defined in TR-4067 on page 7.
http://www.netapp.com/us/media/tr-4067.pdf
Export Policies in Clustered Data ONTAP
Instead of the flat export files found in 7-Mode, clustered Data ONTAP offers export policies as containers for export policy rules to control security. These policies are stored in the replicated database, thus making exports available across every node in the cluster, rather than isolated to a single node. A NetApp cluster can support 40k export policy rules per cluster for systems using less than 16GB of RAM and 140k export policy rules on systems using more than 16GB of RAM. Each HA pair can handle up to 10,240 export policy rules. There is no limit on export policies. Volumes that are created without specifying the policy will get assigned the default policy.
These limits will be updated with each release.