Hey Pete,
Back in the old days of tournament fishing, the prop shaft on my 135 Merc would get straightened 3 to 4 times before the mechanic would order a new one. Those were for the most part small thumps, .015 to .050 out of round. Two years ago I found a new rock pile with the 40 hp Honda, that one was hard!!! Curled two blades and took the bottom of the skeg off. The end of the shaft swung about .140 out. Needless to say that was an idle home. Insurance Co paid about $1200 for that fix. Two things us river folk know (insert "know it all" sniff)... if you run stainless, you're gonna do damage to more than the prop, and ask you're insurance agent about "under water obstruction coverage" The question, stainless or aluminum... STAINLESS!!!!!
George