Moving WP install from local to live, what about wp_posts GUID?

Question

Done this before and i am still wondering what to do with the wp_posts => guid content, which has reference to http://localhost

But at wordpress.org http://codex.wordpress.org/Changing_The_Site_URL it clearly states:

Never, ever, change the contents of the GUID column, under any circumstances.

But as i understand it is just to unique identify your posts globally. But as more people would have http://localhost in their guid.

So can i safely replace http://localhost with http://www.mydomain.com??

regards