Depends on your country when it comes to 'Unrated'.
I've seen R3 and R4 DVDs marketed as 'Unrated' - with the rating plastered acorss the bottom. Some countries will not release an unrated DVD.
We have an 'extreme edition' in R4, and I don't believe it's the unrated version. It's simply the same as the original single disk edition with a second disk of extras.
As far as I know.