Just tested this on Alfresco Community 3.4a using the Drupal CMIS module. When I modify the rootPath it starts browsing the repository from under /Company Home/Sites as I hoped.
However, if I run a query like "select * from cmis:document" or "select * from cmis:folder" it shows me everything including content under the Data Dictonary (respecting permissions of cause, but everything under the data dictionary is read only by everyone).
Obviously the rootPath is not limiting the CMIS queries to just the sites directory. Is this a bug or a 'feature'? For this to work for us the queries need to be limited to a specific directory as well so users can only find content there and nowhere else.
Thanks,
David