This is an excellent question, but I do not have any idea about the result of this command. I should stay that's not a good idea to try in this way and could be achieved with many errors. Perhaps, it should be a good idea to have a report about this ...
Well, i did it and it worked without any problems. However, i can't tell what exactly was overwritten and what wasn't. For example, in Windows 8 I had all Metro apps removed, except Store. Upgrading to Windows 8.1 did not reinstall the default metro apps (which is great).