I've also worked on hundreds of M&A deals as a lawyer. Word's version comparison tools (Track Changes, Compare Changes, etc.) are more than sufficient for track

I've also worked on hundreds of M&A deals as a lawyer. Word's version comparison tools (Track Changes, Compare Changes, etc.) are more than sufficient for tracking or identifying changes in a document. Could it be better? Sure. But the alternative would have to be absolutely amazing to justify the expense of an additional tool and the time spent learning the intricacies of said tool. Word is already good enough at covering the bases that it's almost impossible for an external tool to be worth it. There's a ton of noise. When I was reviewing documents, 80% of the changes that showed up as redline changes weren't real changes but were just formatting updates (e.g., page renumberings, section renumberings). These are real changes. Citations are important for lawyers. For example, in an M&A deal, language in the contract will very frequently refer to another terms, conditions, or other language in another section of the contract. This makes it imperative to be able to track section renumberings, because those internal references matter. (Word does have the ability to create internal cross references that will automatically update when sections are renumbered, but not many people know that this functionality exists...or that it has been part of Word since at least Word 2000.) Also, bold, italics, and other emphasizing formatting can have a semantic bearing on the interpretation of contractual language. They may not be significant to you but they are significant to someone. As far as I know, Word doesn't have any way of making this safe by default. This is the same risk you would have with any comments stored within a document shared with external parties. The solution is not to become dependent on an additional tool; the solution is to build it into the process by having an attorney or paralegal spend 5 seconds to scrub the document using the built-in Word tools designed for this task.