Harmy said:

Well, actually, to be honest, when I made the mask for the cropping, I made the edges round - they are not like that on the BD - I just like it this way, because it gives the whole thing a more film-like feel. I'm actually pretty surprised no-one asked about this before, I kept dreading it since the first workprint :-D

I don't understand why you made the edges round. You will only see round edges when the screen the movie is projected on has round edges (was this actuallyalready the case when the SW movies were in theatres?), not because the projected source has round edges. Also, when someones want round edges he or she can make/buy a screen with round edges. People who don't want round edges now have no choice.