Stacey Spears was the first to confirm the new Serenity encode for the UK release (another pass at it was required to make room for additional language tracks, and as a consequence they got to use later generation VC1 encoders).

As far as I am aware it is the only one a new encode was created for.

DVD Times reviewed both the US and UK releases.

http://www.dvdtimes.co.uk/content.php?contentid=63484 (UK version review)