Timestamp file will be added soon. About synchronization frequency: I was reading CentOS mirror howto: they speak about 2-4 times per day, so I was thinking about 0,6,12,18 UTC for my mirrors.
Since your rsync server has two modules (nethforge and nethserver), do I need to download and use each one in a virtualhost, or use both in the same virtualhost. In case of the last proposition, what about of the ‘centos’ folder which is not downloaded -> http://mirror.nethserver.org/
The easier solution could be to get just one module, and use it to sync the whole repository.
Of course you can add me to the official repository, the server is located in Germany at 1&1. I have planned to migrate to online or ovh, but I will inform you. I do Love free Software (did I never say it ) and it is just one way on my personal involment.
Concerning mirmon, it is a good choice.
The mirror is in sync, maybe a good english writer should start a documentation on how to do a mirror for other people.