I haven't seen Jedi or ESB on BD yet, so can't really say. I have seen ESB a lot of times on film lately, and the original has really variable colour timing.

Some Hoth scenes are blue on film, some are white, some are grey, and there isn't a lot of consistency shot to shot. It is also quite different to any of the laserdisc releases as far as the Hoth sequences go.

I'll watch the Empire BD release side by side with a print in the next month or so, and can report back, but until then, I'm afraid my knowledge has a big hole in it for anything outside of the original Star Wars release.