I often had heavy problems, after change some settings in WordPress or install / update a Plugin/Theme.
So I had the demand to have a test site, which is approximately the same as my production site. so I came up with this self created plugin: Sandbox Mirror.
The plugin copies all files and database entries to a defined server, path and database. so you can test your changes there, before you do it on your production site.
at the moment, this plugin is in beta status and not available for download. please write to me, if you like to have a preview.