[danshaffer]

Unfortunately we dropped the ceiling in our lab (formerly ~30ft) to the point where we can only get the trackball's bottom about 5' off the ground, but our (limited) bounce testing shows that they have a coefficient of restitution (bounciness) of somewhere between 1/2 and 2/3, that is each bounce is about .6 times as high as the previous.
That sounds like a lot of... fun.