Marcs220 wrote:
I am hesitant to change to Stainless, not so much of the added expense, but because I have heard many stories of trashing outdrives if you hit something with the prop.
I've heard this same line of thinking many times over the years, but I don't buy it.  Stainless steel is not indestructible.  I've never seen any evidence presented by anyone credible that proves a negative comparison between the two.
To answer your question, that 4th blade is going to hurt your top end.  I'm not sure that changing pitch is going to be the answer, though.  It almost seems as if you'll be offsetting one v. the other with what you are trying to do.  If true, I think it is a waste of money when compared to just repairing your current prop.
Any way you could rent/demo the one you're looking at instead of having to buy it?
 
					
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Paul
2007 Four Winns Horizon 220Mercruiser 350 Mag MPI w/ Bravo III Drive
2004 Ford Explorer Limited (V8-AWD)
Pomme de Terre Lake (Southwest Missouri)