Under Windows 7, I sometimes run a program called Painter Classic dating of 1990, given to me by an old friend; that program is very similar to Paintbrush, but a little bit more powerful than the most recent version of Paintbrush. The only issue I've met is about associating files with it; I can't open associated files directly by clicking it, but I can open them in the menu of the program itself. Very minor issue.
However, I disagree with the idea of getting rid of so many useful functions provided by Studio, such as previewing the results lively.
By the way, I've tested the option of creating users that would be able to use different version of drivers. Basicallly, users are only allowed to use the driver used by the administrator., but it isn't said that the user can't load its own driver manually. Further testings are to be made, but it's complicated.
I completely agree with you about compatibility of drivers; it's so true that I've noticed that even when you ask for a clean installation of a driver to replace another, the oldest driver remains on the computer. If Windows can be so retrocompatible over the years. Nvidia should be retrocompatible as well, as they are an authority in graphic rendering.
I've encoutered the same popup as you, enjoining me to upgrade to Pinnacle Ultimate version 19. It's something that I don't want to do, since I know that it's not necessary. It's not only for a sake of a few transitions that are not working, but for a sake of a software that I've payed full price, which I expect to work at full strength.
However... I'm willing to test any further.