I have local mirrors of the Fedora repositories to serve the internal requirements without downloading each update for every machine. We do not install games nor KDE applications, but everytime there is an update for those packages the network is used. There are solutions like SpaceWalk for the updates problem, but at the same time we need to have some packages available to install if needed, not only updates. Another options is to use an intelligent mirror that check package groups and download only the groups you are interested from the mirror, but that adds another complexity over the standard mirror tool that is rsync Maybe creating a repository layout like repodata base x gnome kde development ... could make easy for mirrors to tell rsync to ignore some directories. createrepo already support a nested structure, What do you think about that?.