Last weekend I tore up my prop on a big rock or something in the river bad enough that it has to be replaced. The motor is an '06 Mercury 60hp 4 stroke. I'm thinking about trying a 4 bladed stainless steel prop but I though I'd see if anyone else had any thoughts on it or any suggestions on what they would do different?

I would stick with the same aluminum prop that came with the motor. 

The stainless steel props are very strong, cost more, but a lot more expensive to repair.

You can get your aluminum prop repaired.

If you fish rivers a lot with similar hazards, your best option is another aluminum prop or Comp Prop as a spare.

The aluminum will break easier and may save a repair job on the motor drive train.

I usually fish lakes and don't have to worry much about hitting anything. I look at some reviews last night and it does make sense that if your prop folds or breaks it might save expensive repairs to the motor so I'll probably just get an aluminum prop and maybe a comprop as an emergency spare, thanks guys!