When migrating a fileshare to SharePoint there is a tendency to copy the filestructure one-on-one to a library, and to maintain a permission setup based on folders. Sometimes I read articles that is not best practices to structure permissions by folders, but that permissions should be set in sites and libraries. But then the disadvantages are not explained. I know the fundamentals on setting permissions in sharepoint groups populated with securitygroups for Sites and libraries, but I find it hard to grasp the pro's and cons on using folders instead. For one thing, it is also possible to grant permissions to a group for a folder. There must be strong arguments to change a way of working that is familiar for a organisation. I wonder if any of you guys, would know these arguments, or else, don't mind a folder permission structure at all.