Dale, The flat leading edge is certainly odd to see. I am no prop expert by ANY STRETCH but believe a smoothly rounded, semi-sharp leading edge to be the best. A knife edge can lead to some cavitation. Although I have to believe the flat edge would be worse than the knife edge for cavitation as well as performance. I dont know the application for a Michigan PJ 016, but it looks like a fairly small prop, maybe for an OMC 4hp around late 60s to early 70s. I could be completely off though. Just going by shape in the photo.

Maybe someone with more knowledge of props will be able to help out more.
-Ben