The recommended way of upgrading is booting the new bsd.rd (..directly, or via other media) and typing 'U' when prompted.
After installation /etc is preserved, you need to manually update configuration files. How this can be done is outlined on the upgrade??.html page.
The 'in-place' upgrade is used for remote systems not easily accessible, it involves manually extracting the sets.. for a novice, a lot could go wrong.
BTW, that book/article was published in 2005, you should always refer to official documentation instead of outdated 3rd party guides.
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