Ady, something else to look at where the mattes meet the set footage on the SD bridge. Can these be smoothed and blended more/better? Where Vader walks the floor looks white/light gray and it is darker where the matte begins on the floor. I have arrows pointing where the mattes and live action meet and could be blended better. Just a suggestion. Here is the still to look at.
http://img15.imageshack.us/img15/387/newestcomparisonslook.jpg