Using rsync push is a good idea, and it's a standard method anyway. I've been putting off mirroring as I watch what has been happening with Arch getting signed packages finalized, part of the upcoming pacman version 4, and also because just keeping up with daily updates and progressing other more critical areas has zapped all of what little free time I have had. I'll finally have a good section of free time over the holidays coming up, and my goal is to have the changes I want in the build system done by mid-January. Those changes are also pretty much necessary for doing proper mirrors, since right now the garbage collection on old/moved/removed packages is still a manual process.
I'll keep you posted though and let you know when we're ready. Shouldn't be too long.