I heard from John McGhie that the issues were fixed in the Mac version of Word 2016. I am unsure as to the Windows version. Master Documents is not a feature for the Android or iPad versions. I asked John whether it had been fixed in the Windows version and he has not answered. The downside is pretty catastrophic. That line you quoted is from John. They were not fixed as of Word 2013, AFAIK.

I have not had the interest to work with it since Word 2003 because the downside is so catastrophic and MDs by definition involve a lot of work.

Master Documents "Feature"