Although MS Office 2016 seems shiny, slick and new, don't let it fool you; as you say, there may be compatibility issues with "niche" softwares. I use WordFast Classic and it won't work with Excel and PowerPoint files in 2016. Windows 2010 or W7 worked better for me, and I keep a couple of backup PCs loaded with these operating systems just in case.
For years I have made it a point to keep all of my installed software packages and their corresponding licenses or product keys, just in case. Of course, I keep them both in their original CD or DVD format and on a separate external hard drive, which I back up.
The lowest common denominator for software compatibility is to keep and use the oldest yet functional software programs that play well together. Exactly the opposite of what software companies expect us to do: to be early adopters.