I've managed to play slow-paced FPS'es with the trackball (e.g. PUBG) and remain - well, not "competitive" exactly, but not total trash either. You can generally dial it in for great accuracy but slow turning, or less accuracy but fast turning. But not really both at the same time, unlike a mouse. (since there you can your elbow for large movements, and your wrists for smaller ones) With the latter option, you would not be able to hit small targets quickly. In terms of desktop use, you can generally find a balance where it can get across the screen in a single swipe, but you can still hit a button immediately, so it's an OK trade off for me.

So I just now remembered why I don't use trackball. I have two huge monitors side by side and jumping from the end of one to the end of other was really uncomfortable with trackball whereas it is a snap of the wrist with the mouse

I move the width of the mouse to span two monitors yet I have no trouble clicking on a 4 dot cluster on 27inch 4k monitor (which would be equivalent of a single pixel on full HD).

Now I am not sure I want to use regular mouse with a PC and trackball with a laptop. In my mind this is either or choice.

I've opposite experience. Moving cursor in wide display is comfortable by thumb trackball rather than mouse. Just move thumb, don't need snap of the wrist.

You just have to set the speed higher. I work on 3 screens with it. For precision, the ergo has a small button near the ball which makes slow.

More precise but slower (at least in my case).

I switched because I've been doing CAD too much lately.

It is more precise and once you're into it, you're faster too.