[Zope] Storing Roles in RDB with APE

Hi, does anybody have experiences with storing roles in an external database with APE. What are possible problems with that. concerning stability, reliability etc. Are there other or better solutions storing roles externally. For the first step, only roles of one folder-object need to be stored. Is it possible, to store all roles of any folder externally. The informations about the roles should only be kept in the external database, so changes of the concerned table should change the roles in zope. -- Thanks for your answers, Elena