Stainless props hold up better when they impact a stationary object but at the cost of possible damage to the lower unit gears.
The good thing about aluminum props is their softness (softer than the lower unit gears) so it breaks while saving the gears that are worth a lot more $$$$. Change to a stainless prop that is harder/stronger than the gears and the dears are likely to be the first thing to break.
But at least your prop will be ok.
Better to go through $100 worth of props rather than $1000 worth of lower unit repairs per incident.
Where stainless shines is in areas where hitting rocks, stumps etc are not an issue.
Stainless props afford better performance (better holeshot, turning, top end speed) that is what they are designed for not for stump bashing.
Bottom line stick with your aluminum, your lower unit will thank you.