Let's get one thing straight right now: there is no such thing as '85 mixes of ESB and RotJ.
I'll say it again: ESB and RotJ were never remixed in 1985.
How do I know this? Because a while back Darth Mallwalker sent me samples taken from many different pre-1993 laserdiscs, and try as I might I could discern no significant audible differences between them whatsoever.
I did observe the same phenomenon earlier mentioned here, which is that the waveforms sometimes look rather different from each other, but there are explanations for that which have nothing to do with remixing, and everything to do with the properties of analogue audio. In addition to making new video masters, they seem to have gone back to the source tapes and copied them again every time a new home video release was made, and it is indisputable that no two analogue recordings are ever going to be exactly the same as each other. The reasons for this are plentiful, including small variations in the speed of the tape machine during playback, imperfections in the physical nature of the tape and how it may shift over time, the fidelity of the electronics inside the recording equipment and how that may change over time, the fact that tape compresses transients and adds harmonic distortion when recorded at higher levels, and other things of that nature.
Additionally, early analogue-to-digital converters were less accurate than what is used today and may have introduced alterations of their own into the sound. The result of all this is that no two copies will show identical results when looked at in a waveform editor, even though they are obviously still the same mix and the actual audible differences between them are quite subtle. Going purely on listening to the stereo balance and mix levels, I find no reason at all to think that any kind of remixing of the latter two films was ever performed until 1993. All versions showed the same overall dynamic range and had been panned inwards in a similar fashion to the '77 stereo mix of SW, which I'm certain was to minimize crosstalk in the surround channel when upmixed. No version showed the full width stereo spread that the '85 version of SW contains; for ESB and RotJ this kind of imaging can only be found in the '93 mixes.
Speaking of the '93 versions, there is no real reason to avoid them, because unlike the first movie there aren't any sound effects additions. ESB is missing the snowspeeder crash sound for some reason (I reinserted this for my 5.1 track), and RotJ may have its music mixed slightly lower than the original sometimes (I'll have to check this more thoroughly to be sure about it), but on the whole the huge dynamic increase is certainly worthwhile and they both 'feel' authentic; though unlike SW they were not taken from their respective 70mm versions and aren't quite the same as what those would have been.