I can't say for sure how the 70mm soundtrack compares to todays movie mixes, but I do remember the floor and seats shaking when I originally saw SW in 70mm in '79. Wow that was cool and hugely impressive and it has been one of those pivotal movie experiences for me. The theater I saw it in was the most advanced theater in the southern hemisphere at that time and may possibly have had a sprung floor, which may be part of the reason the floor and seats were shaking so much. I'm just guessing about the sprung floor though because I've never experienced anything like that in any theater since. I also remember watching it in dolby stereo about 6 months later in a different theater and still feeling like the Tantive flyover was going to bring the ceiling down or rattle my teeth out of my head.

For what it's worth, the re-releases of Star Wars and the SE etc have never rattled my teeth at all. Most movies these days just don't seem to have the same level of oomph!