Speaking from working on the Red Hat/Fedora side of mirroring for a while... mirrors do not like to be pushed to. They also do not like having to run software that would initiate a pull if notified of new content. For most of them, this is a spare time, feel good item. They have no time and usually have to spend a good portion of the year explaining to their bosses why they even have a mirror to the internet since that costs someone a lot of money somewhere. So anything which adds to that workload is a minus.