1st backup you site.. (www.akeebabackup.com works well)
2nd copy your backup to a different host/computer
3rd Have a little linux knowledge before you start
4th Do not have you staging site in a physical subdirectory of the main site (it makes the rsync setup confusing and painful)
This plugin uses rsync, and if you configure it wrong it will delete you entire install.. (you have been warned!! - but its worth struggling through)
Ok, This tool once configured works very well copying both the file and DB contents from one site to another. It interferes with bi-directional copying by removing its self from the target.
So in my case I copied from Live to my new staging site (worked well) and had to reinstall to copy from my new staging site to live (also worked well, 2nd time. 1st time I messed up the config and had to restore from backup)
Maybe the author could add mode to preview the rsync dry run. This would begin to make this tool a little safer.