First of all, somehow my parents did a good job raising me but dropped the ball with my brother. Otherwise there is no explanation for the ski boat.... ;o)

The lost area looked just about like yours. He faired in the chipped area then made a cardboard template and trimmed the other blades to match. He claimed to not be able to tell the difference in performance. It lasted a couple of years until he hit something else and totally busted the prop. (He is a power boater you know)

I think I would not leave the blades imblanced. It could do bad things to your cutlass bearing and shaft - maybe.

BTW that is a verry interesting looking chunk gone. It almost looks like it was cut with a sharp tool. Maybe you did hit something metallic.