Ballllllllllllllllsssssssssssssssss oooooooooooo sssttttttteeeeeeeeeeeeeeeeelllllllllllllll.
I dunno. Those Zirconium Dioxide bearings will wear down faster than Amy Winehouse's looks. But then again, I don't proclaim myself the World's Foremost Trackball Expert.
Hands/fingers/skin promotes corrosion to metal based surfaces. It certainly looks cool though.
The concerns about the optical sensors depend on the implementation. If your trackball has the sensor peeping at the ball, you are fked. But if the sensors are watching slit wheels, then the surface of the ball doesn't matter.
Do you see a red light at the bottom of your trackball?