danny_boy said:

Having said that the public have never been shown which or what frames(that featured optical composites) have/had deteriorated.

A lot of the original composites are still in the special edition----and they look to be in excellent condition(although they exihibit the extra grain and contrast associated with 3rd generation elements)

There's a possibility you would be surprised how few of those there is that are original, there wasn't actually that many of them left in the 2004 DVD version. They could perhaps be counted on one hand or two, this isn't actually a matter of degraded material either any more, it just happen to be a perfect opportunity for Lucas to redo the film, as many shots they recomposited in '97, just as many were done for the DVD, and then it isn't about deteriorated material any longer, it's about replacing every optical shot to get rid of all the grain and ultimately none of the original academy award winning ground breaking special effects work are left to be seen.

I have actually not seen the blu-ray transfer myself, but is there actually additional grain and increased contrast on any of the effects work? I find it hard to believe when Lowry made a big deal of getting rid of such things in 2004.