Personally, I still prefer wood props Ive never gotten seriously injured from a wood prop. I have, on the other hand, cut my finger badly simply removing an APC from its package. And, I once used a Master Airscrew 11x7 to slice up a watermellon at the flying field.

Master Airscrew blades are pretty well designed. I think, however, anything above their 11" size - I will avoid. I tend to prefer MA for seaplane use - they seem to hold up to water spray the best. The MA 9x6 was the standard prop for years in NEPRO Q-500 racing (K&B .40 engines).

APC offers the advantage of moredifferent sizes and blade profiles. Allows for matching the application better. Both the APC and Master Airscrew props (and other molded designs) offer consistancy as well.... the next prop will perform the same as the one you just broke (a characteristic flaw of wood props)

As was noted in the T-34 performance example above, prop selection is key. It is much like selecting a gear in a truck or car - allows the engine to perform best depending on whether you are driving up hill, over sand, in the woods, stop and go in city traffic, or cruising on a flat highway.

Matching an engine/airframe/prop for a given requirement is not always necessary. We all know the general rules of thumb as to what prop tends to work well with each engine. But when you wish to optimizes for max speed - take-off performance - lower flight speed - downline braking - landing braking - scale cowl - high drag - low drag - 3D - aerobatics - vertical climb ---- it is nice to have a wide variety of props to select from.

Good example ----- two very similar engines, very different jobs...
My SS-40 Q-500 sport engine runs at 21,000 rpm with an APC 8.5x7.25 prop. Provides the best take-off dash, and top end lap speeds.

My SJ-46 installed in my P-51 mustang with the turbo-jett exhaust, is turning a 12x4 14,000 rpm. Launches at 13,600. Provides outstanding take-off and landing performance with great airflow over the tail surfaces - LIMITS my top end speed and downline speed a bit for more consistant flight speeds at all throttle settings (more scale like) - and it provides a 1900 rpm idle This prop selected after trying everything from a 9x7, 10x6, 10x7 and a 11x5.... simply proved to be the best.

Also, where the APC/MA line also crosses, is the recommended max RPM the blade will see. In many cases, APC offers props better capable of the higher rpm and dynamic loads. Do your homework, and select properly for the engine and application.

Ok....... im done