I had a disheartening experience with one of my customers, an established music publisher I'm sorry to say, who opened and made proof reading changes in carefully polished musx. files without turning off Automatic Music Spacing. The result was that the printed and published score looked rather awkward and amateurish with a lot of collisions and displacements that certainly weren't there in the files that I delivered.
My suggestion is that the option to turn on and off Automatic Music Spacing is moved from program-based Preferences to document-based Document Options to avoid mishaps of this kind. (I also had problems myself more than once, when I moved from one project to another and forgot to turn off the function – and lost hours of work.)
Finale (97, 2003), 2007, 2008, 2009, 2011, 2012, 2014, 25.2
Mac OS 10.8