Don't change Alfresco's out of the box content model. If you can possibly avoid it, do not change Alfresco's out of the box content model. Instead, extend it with your own custom content model. If requirements call for several different types of content to be stored in the repository, create a content type for each one that extends from cm:content or from an enterprise-wide root content type.

Consider implementing an enterprise-wide root type. Although the need for a common ancestor type is lessened through the use of aspects, it still might be a good idea to define an enterprise-wide root content type such as sc:doc from which all other content types in the repository inherit, if for no other reason, than it gives content managers a "catch-all" type to use when no other type will do.

Be conservative early on by adding only what you know you...