Are there any other Trek novel "director's cuts" that I should be aware of?
Several of the seven "Signature Editions" omnibuses were able to be tweaked by the original authors. Greg Cox fixed some minor stardate problems in "The Q Continuum". "Pantheon", which reprints "TNG: Reunion" and "TNG: The Valiant" by Michael Jan Friedman, has an all-new bridging arc that connects the two tales (ie. seven extra paragraphs from a reflective Guinan.) The bookend historical chapters for "The Valiant" are widened to embrace both stories in the SE.
IIRC, the corrections to the novelizations of "ST II: The Wrath of Khan", "ST III: The Search for Spock" and "ST IV: The Voyage Home" in "Duty, Honor, Redemption" were made by Marco Palmieri, not Vonda N McIntyre. (The omnibus has had minor errors corrected, such as "McGivers" for "McGiver".) References to Sulu's promotion to captain (in McIntyre's ST II) is removed, since the line was dropped from ST II and then ignored by the other movies.
The omnibus for the Reeves-Stevens' "DS9: Millennium", which is not a "Signature Edition", has a bonus Allyn Gibson timeline (of the complex plots) that didn't appear in the original MMPBs.
The MMPB omnibus collecting MJF's "Starfleet: Year One", which was originally serialized over a whole year, has new material and new characters. Its original chapters were divided up and blended with each other, too.
The second printing of the "Stargazer: Oblivion" MMPB corrected a printing error that had seen the outer margins of several letters' worth of text vanish from about eight pages of all the first printings.
The UK and Australian versions of the TMP novelization have extra sentences in several places, better describing the relationship between Kirk and Ciana. They also contain a generous section of captioned colour plates: publicity pics for the movie. The US Pocket slipcased hardcover has a dedication "To Majel".
The MMPB version of the "Generations" novelization features the as-screened Kirk death scene, revised by Dillard herself. The original hardcover has the scene as featured in the bonus scenes of the DVD.