Bronze props actualy suck, nibral is what you want. My grandfathers Chris Craft had nibral props and monel shafts.
Those are what good boats use, but they cost more. Nibral is nickle, brass, and I think aluminum, something like that. Holds up very well.
Stainless props are fine, but if you hit something the risk of doing damage is higher. They make composit props for larger motors that you plan on running around rocks. The blades are cheap and can be replace on the water for about $40 each. They just share right off.
I have seen the entire lower units ripped off stern drives and outboards, they share right off! The worst was on a Skater go fast with a Merc racing drive, he ripped the entire lower half off...its a $50k drive, not counting the prop...
We saw it right as he was pulling it out on the lift, puking gear oil still. That was an expensive mistake.