In our company we merged SharePoint and Confluence into Connections. Now our users are complaining because both tools had a much more advanced authorization management which can not be reproduced with Communities.
For example with Confluence it was possible to provide access to a wiki page for only a specific number of users. This would be very helpful since we have departments which have to manage partly public but also confidential information with there Community. Currently they have to use two or more Communities to manage the authorization concept. This is a huge effort for all of the effected users.
Same thing with files. It is not possible to restrict special folders or files within a community. This situation makes the work from our users much more complex than it could be.