>Interesting idea, but I have no idea where one would obtain NT4/2K licenses these days... or even installation media. Sticking to XP SP3 might be preferable (last version to use only SMB1) but licenses/media for that probably aren't much easier to obtain (except maybe MSDN?)

I have some old MSDN discs which allow me for unrestricted time to set up new machines with those OS. I use XP VMs for tasks not needing bleeding edge (as newest versions more and more do not support XP any more), but you could create performant VMs with much less memory footprint than XP with the older versions. Remember the early NT4 machines needing 16MB minimum and 32MB reccomended? I jumped from my first multi-OS install with NT4 from 32MB directly to 128MB, which was unheard of back then. XP can work below 512 MB, but somewhere in the range of 256..384 MB starts to crawl.
Now if you want to run a significant # of VMs on one motherboard that might make a difference ;-)

>
>Another tool worth mentioning/consideration in some circumstances is running a VFP app in Compatibility mode. You might recall I ran into an obscure bug running VFP9 on Windows 10 some time ago; until I could implement a workaround the temporary fix was to have users run the app in Win7 compatibility mode.

Good point to mention. Still: using (better: being forced to use!) such options feels to me like the aequivalent of monkeypatching code to "fix" bugs without going to the bottom, as you have no idea whether the "fix" will still work after the next OS patch day and in a perfect world you had time and budget to test after each patch day....