I have heard that too Boatnluvr. Aluminum will give whereas stainless will not as easily. Thus, with aluminum you get a severely boogered prop if you hit something, but less (if any) damage to the gearcase.

Do you guys hit a lot of rocks in your area?

No, it is not normally rocky but I found the one rock that was there.

That's my Luck.

Stainless for me as well.

I've dented my SS prop a few times, nothing major just a few dents here and there. An aluminum prop would have been destroyed or badly damaged like that one.

Banged up prop
 

I did a bit of roto-tilling with a 19p stainless on our Sea Ray it cost 150 to repair it............

Find a used one. I saw one at a marine styled swap meet I was 2 seconds too late for,...another guy paid 10.oo for it.

Also prop shops sometimes have reworked ones the owner never picked up.
By all means tho',...stainless is the way to go.