Well, I don’t know - I’ve heard people say that they saw the SW movies in both 70mm and 35mm and 70mm was definitely better looking and it would seem to make sense, because even if you went through exactly the same process, except in the last step instead of 35mm film, you used 70mm film, which is undeniably able to hold more detail than 35mm, you should get more detail.
Does anyone know how exactly the 70mm blowups were made? What would make the most sense in terms of quality would be to do the blow-up directly from the ONeg, essentially getting a separate 70mm IP and then copying to 70mm IN and from there to 70mm prints - that would probably get you much much closer to the detail of the ONeg than a 35mm print but somehow I don’t think they did that.