usually the data of NC is owned by www-data user. this user should be as good as any other. Personally I would not touch it as you hit other problems then: webserver needs full access to the files and storing the files in ~ of another user could result in some drawbacks. If you still want to go this path maybe this thread is useful for you:
depending on your system you will find number of working backup solutions, just use search in this forum or follow official backup guide