You are right; the EU BD has lower bitrate in comparison to the US BD, but, again, IIRC, differences are so tiny that maybe could be spotted only using a video projector with a big screen, sitting very close... (^^,)
There are a lot of grain in the EU BD, too - I mean, the "good" grain. English DTS-HD MA will be left "as is". I have not the isolated score, but if someone could provide it, I'll be more than happy to add it, too.
About the extras: I should study and see if the EU BD and EU DVD have the same extras or not; maybe I could always do another BD filled with extras, if there will be enough interest in it...