Neil,
Without warranting a definitive comparison, the only textual omissions in the trade edition I found are in the closing chapter "Some thoughts on Golf".
Four paragraphs about the approach of the Ladies Golf Union of Britain to handicapping are omitted from the "Handicapping" section. I have no idea why they were struck. Two paragraphs are missing from the middle portion of "Financing Golf courses". Finally, two paragraphs are missing from the section on "Camouflage".
The omissions from these latter two sections might be characterized as, respectively, purely political and military in nature. The editors may have felt MacKenzie strayed from gca in them. However, I agree with the comments that they should have stayed in, as these topics are germane to MacKenzie's conception of gca, and the writing gives you a bit more sense of the writer.
Certainly Sleeping Bear didn't mislead us with respect to the editing of the trade edition. In the Acknowledgements section, it says that "The book that you have is almost precisely as MacKenzie wrote it....", which on balance is a correct statement.
Ken