Using MS active directory vs. Novell eDirectory for portal AUTHS

I am aware that either active directory or edirectory can be used to authenticate to the SAP portal.

However, for authorizations in the portal, is there an advantage of one over the other? Our portal will not only use authorizations for displaying tabs, but to perform restrictions inside custom applications.

If you had built your portal architecture (authentication and authorization) around one, how easy would it be to convert to the other?