Those 5.1s would be the ones done for the last LD series, the THX CLV pressings form 1998 or so. There were many announced but canceled, and you can see the listing on LDDB for these such as LTK, FYEO etc. and all were to have 5.1 mixes on the ac3 track. All that came out of course were DN, FRWL, GF, TB, TSWLM and MR. These are the same as the THX DVDs but have PCM original audio, and the DVDs have progressive video.
The THX discs are the same as the SE discs, same master, same compression bitrate everything but the SEs just crammed in every special feature on the disc plus the new menus. There may be slightly less compression on the THX discs, but if I'm thinking correctly they all have a separately encoded fullscreen version on the disc.
These 5.1 mixes will almost certainly trump anything from later on simply due to better compression and greater detail. Better practices because they were made for LD 5.1 which avoids the typical down conversions built into DVD audio. But the UE is the only release of LTK that is fully uncut in Region 1. The others are a rumored PAL German LD and a NTSC Japanese LD but both are full screen.
I'm not surprised that there possibly aren't any corrected SEs. They're not any huge errors that aren't fixable. My question is if these are indeed the best video source we have for the original presentations or if a finely conducted LD transfer could match or exceed them. Some have decent images, and then some are riddled with compression artifacts and other nasties and then over-sharpened to within an inch of their life. And then DN/FRWL/GF/LALD/TMWTGG are cropped to 1.78. And on top of all that there are moments of combing and interlacing that sporadically appear in all the SEs I've sat through.
