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.
To maybe answer RayRogers’ inquiry, I made a search “forbidden planet” site:originaltrilogy.com (happen to use Google) to see if anyone had worked up a Forbidden Planet project. Didn’t find one, but did find this from October 2013 about it’s Blu-ray:
Does anyone have any comments on the DTS-HD MA 5.1 on the BD of Forbidden Planet (1956)?
As most know, FORBIDDEN PLANET originally had a wide release with a Perspecta Sound encoded track, along with a few limited engagements in (true) 4-track mag sound.
The three front channels are original for sure. They match the very old Criterion laserdisc version as far as front channel image placement goes. The bluray’s DTS-MA audio has the advantage of being discrete, vs being matrix encoded like the previous home video versions. The MGM DVD and first WB DVD (same version of the MGM DVD pressing) had screwed up audio with no real directionality in dialog or effects. The Bluray corrects this, and as noted above, also offers the audio for the first time since the 1950’s in discrete multi-channel. Can’t say for sure about the effect/surround track, but it wouldn’t surprise me if it is the original.