Have you guys considered it might be the digital cleanup that causes the socalled compression problems (I'm also addressing the members who have seen the preview)? Considering what Adywan said, I find it hard to believe it is the actual compression that is the culprit. However, digital cleanup and compression have a lot in common. I'm reminded of this post, where the cleanup clearly destroyed a lot of detail:

http://originaltrilogy.com/forum/topic.cfm/team-negative1-star-wars-1977-35mm-theatrical-version-release-details-and-updates/post/771245/#TopicPost771245

Looking at that comparison, it is clear that apart from the obvious problem, a certain amount of depth and clarity appears to have been lost, although it is difficult to see at that resolution.

I think it might be a good idea for the team to post some screenshot comparisons at high quality to see what's been gained and what has been lost.