Erikstormtrooper said:

Have you happened to listen to the mono track for any dialog or effect differences?

As far as I know there should not be any differences in terms of content between the 70mm and 35mm audio tracks, other than the opening theme, which apparently was tracked from Empire in the 70mm. The mono track on this is most likely a fold-down of the 35mm Dolby Stereo. Only Star Wars were given an exclusive mono mix.

Video Collector said:

Is there any reason to believe this 16mm copy differs in any way from what was released theatrically in 1983. (Placement of subtitles, for instance?)

Because, cropping aside, this would be the best version to call a "Theater Performance Edition", subplanting the bootleg versions None and I have archived.

The subtitle and its placement looks exactly like the theatrical subs to me, great reference material for those trying to recreate them in various edits.

EDIT: Going by those screenshots posted by adywan it sure looks like it's better than just being good reference material for subs. My comment sounded patronizing.