How much is "too expensive"?
Our dealer provides scissor style trailer use at no charge if you store with them.
Trailers are nuts right now.
Was told of one well known brand that has increased in price 33% since November.
FWIW, I have seen firsthand one Mercury 150 that was very difficult to shift with Alum prop.
Dealer put on a SS prop and instantly shifted smoothly.
The extra rotating weight is definitely beneficial.
Now this particular engine may simply not be as well balanced as most, because I'e seen dozens...
Higher octane equates to resistance to detonation. Detonation is terribly destructive when it is not when it is supposed to be.
For cocktail cruising you would probably be fine, but if working the engine at all, you need to keep your octane in the recommended range.