Well, from what I've heard, Lucas can be seen discovering a minor flaw in ESB in one of the docs on the Episode III DVD. He responds with a "We'll fix that next time". So I doubt these are final versions. The 2007 "archival edition" will probably be the one where they smooth out all those little errors, but this time he'd better do it right! That man probably won't stop tinkering till the day he dies

As for the DVDs really being WIP-versions, who knows? It certainly seems to sloppy to be a final product and knowing how serious Lucas is when it comes to "his vision", I doubt he even knew it had so many errors in it. So that seems more logical to me as well - I doubt Vader's pink saber was a "creative decision".