Actually, the pitch thingie is not all that uncommon. Consider: if your
prop has a 6" diameter hub, and the prop is mounted such that there is
a tilt across the long axis where one side is .01" off relative to the
other, one blade will be at 0.1 degree more pitch, and the other will
be at 0.1 degree less pitch. With CL slope being 0.1/deg, if the prop
blades are designed for a CL of 0.35, one blade will be at a CL of
0.34, and the other will be at a CL of 0.36. That's a 5.9% difference
in thrust between the two blades. You won't see this with tracking.
Let's say you have an airplane with an O-320 and are operating at 75%
power with a prop efficiency of 80% at 200 mph. Your prop is developing
180 lb thrust total; one blade is developing 87.4 lb thrust, the other
is developing 92.6 lb thrust. There is a 5.1lb differential between the
two blades, which tries to whirl the motor on its mounts. You will
never get the prop balanced, and the more thrust you develope, the more
shake you get. Been there, done that!