Did you go from running at lower RPM with the 18x16 to higher RPM with the Campbell Sailer? What boat did you have and what was the engine HP and reduction? That's a huge change in prop pitch in addition to a smaller diameter.
On the Martec props; I have heard about the pins wearing the bronze at the hinges; how long does a Martec prop typically last before the prop needs repair or replacement? Seems that galvanic corrosion and wear due to thrust on those pin holes is inevitable due to the design.