For what it is worth I personally would never use a ball link on a single phenolic arm. A ball link is offset from the arm and so it introduces a twisting effect to the arm that eventually can cause failure under load. The double phenolic arms found on some models are great in that you can place the ball link between them keeping the load inline. I agree that the pin type can wear but as long as you check them for play once in a while a good quality clevis with a fairly large size pin should last for quite a while and I would much rather deal with a little wear than a broken arm in flight. JMHO

Bill