Skip the special-shaped mousepad if you use a trackball.

No, they don’t provide any practical advantage. The shape of a mousepad is irrelevant because a trackball doesn’t move—only the ball inside does. What matters is the surface texture for smooth tracking, and a normal rectangular pad does that just fine.

Some people argue that a cutout or curve helps wrist posture with a thumb-operated trackball, but that’s about desk setup, not the pad itself. A standard rectangular pad gives you enough room to rest your hand and protects your desk. Anything fancier is just aesthetics or marketing.

Your trackball doesn’t care what shape the pad under it is.