I read on imdb that the two non-mono mixes were updated with the "A New Hope" name and the mono was not. Certainly that implies the non-mono mixes were plenty in use for the 1981ANH reissue, at least as much as the mono.

I've read elsewhere that the 4th mix was 1985 vhs (which skyjedi refers to), so I guess that means they didn't stuff mono lines (like "Close the blast doors") into non-mono mixes in 81, because that would have been a new mix before 1985?

Re what's in the 1985 mix, I've got a book called "The Scripts" that's a collection of the continuity scripts for the OOT. It was published in 1995 in Britain. The scripts inside are supposed to match the films exactly. The book came out as a companion to the 1995 vhs release of the OOT. I suspect its version of the script matches the 1995 vhs version.

Would I be right in saying the 1995 vhs's audio is the 1985 mix made for the 1985 vhs?

The book has 3PO's tractor beam line like the 1985 vhs mix but lacks "Close the blast doors" and it has "Blast it Biggs" like the non-mono and when the stormtroopers nearly find the droids in Mos Eisley they say the door is "locked" not "secure" and locked is the non-mono version. So if I'm right, that's what lines are in the 1985 mix. Basically the non-mono version plus the tractor beam line.