I just watched your video “How To Know Whether You Can Upgrade to Sierra (#1313)”, and I think you just took into account the hardware point of view. But the software side is also very important.
I presently use many applications with my Mac, and it is very important for me to know if they will run without problems with Sierra. For instance, will Final Cut Express 4.0.1 run within Sierra.
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André Boileau
That's a good question. There is no easy answer. I've seen lists of apps, but they are often incomplete, not updated, and sometimes don't give enough detail, like version numbers.
So you have to figure it out on a case-by-case basis. You could take a look at which apps you are concerned about and look them up. For third-party vendors, they should list this on their websites. If not, email them and ask.
The problem with Final Cut Express is that it was discontinued in June 2011. A search turned up some reports of it working with El Capitan, which means it could very well work with Sierra. But many people also report some functionality loss as early as Mavericks. To be honest, since it was discontinued so long ago, I'm surprised that it works for anyone.
Note that FC Express was essentially replaced by Final Cut Pro, which is available in the Mac App Store for the same price Express was back then, back when Final Cut Pro was much much more costly.
My advice is to move on from FCE as soon as possible. Relying on obsolete software is sure to become a problem at some point. Either move on to current Final Cut Pro, or try iMovie. iMovie gained some of the functionality of FCE over the years, so maybe that is all you need.
I have the same advice for other apps. If the developer decides not to update the software, then I try to find a replacement and move forward.
When dealing with apps that use drivers (such as printers and scanners), you can also go to the app's website and see if they have a driver for the OS you are upgrading to.
I've encountered situations where the app does not get around to updating a drive to a new OS I have for months! I've also upgraded my OS only to find that the app company no longer wishes to support the new OS.