I've just purchased XenForo and I love it. One thing I noticed is that you can create Private forum categories, where people can post something and another user group can have permission to view it. However, people that post in this topic can only view their own posts and nothing important, for example, a sticky thread.
I'd like it so that people can view their own threads and view sticky threads with information from forum staff in them. Moderators or assigned user groups should still be able to view everyone's threads.
An example would be at http://hypixel.net