You don't have to back up the entire User folder before reinstalling OS. You'll just have to back up preference files and others and then put them back where they belong after OS reinsallation. Which file to back up? HomeAdvisory will assist you. Depending on the application you select, HomeAdvisory will tell you which file to copy and why.
What's so special about HomeSync? After backing up files, reinstalling OS and applications, press Copyback. And HomeSynch can put stored files and folders back to where they belong.
Note that the Lite version no longer allows the user to use Copyback.
Click here for User's Guide.