Keeping your backups in sync (Mac)

Just want to give a heads up in relation to the software that I have found to be excellent and that's Chronosync. I've got three 4TB HDs, one being the main music library for playback, one a copy of that but attached to another computer, mainly for updating tags and my Music Collector and the third drive is kept off site as a backup. The task here was to find software that would keep the newest changes updated on all three HDs and Chronsync has proven to be great. And it's fast!

ChronoSync Overview | Econ Technologies Software »

I had tried Path Finder for a couple of weeks but gave up on it.