[emmanueloga_]

The point of the article is that someone visiting the old URL should the old resource as opposed to a 404, an error, or some different content. If you can't keep the old URL the second best thing to do is a redirect. (EDIT: I guess being pedantic the point is to design the URLs so you don't need to change them later, but "get it perfect the first time" is kinda useless advice :-)

This is what 301 HTTP status (permanent redirect) should be for... [1] So it seems to me if you use 301 you should be good to go.

Also from a quick search it seems the recommended thing to do is remove the old URLs from your sitemap.

1: https://en.wikipedia.org/wiki/URL_redirection#HTTP_status_co...

[jerven]

Yes, and adding a note doing the 301 will preserve the search engine mojo.