I did direct comparisons with the opening, Robby’s first appearance and introduction, and the first arrival at the house (reel change point).

The mix seems the same. Both the Criterion and MGM have the sound panning. But the Criterion is limited in dynamic range and centered practically around the center channel only. This is with and without ProLogic engaged. The MGM is fuller and has more depth and is firmly stereo with the same slight panning.
Overall it sounds like a mono and stereo of the same source. The weird thing is they’re both technically stereo and both decode properly in PL. I can only describe the sound structure though and what actually is coming through my system.

Not to mention they both look closer to the 16mm caps above.

This review indicates the old pan and scan disc has the best color:
http://easyweb.easynet.co.uk/~robinson/Reviews/Forbidden-Planet-Review.htm