Thank you every one for you recommendations. After some consideration, I've decided to embrace the randomness of the disappearance and have chosen...
I just gave that a shot. The Kill Ball now disappears and never comes back. When I set the spawn timer to "1" it at least pops back in to place....
I've been working on a map where I have a Kill Ball spawning in front of a man cannon which in turn sends it rolling thru a trough to another man...