Re: RPM Versus Wear
If you are referring to a certificated engine, then I do not know.
If you are referring to an automotive engine, then I would say that you should choose your redrive ratio to place the engine in its correct power band. I don't think you will "wear out" an automotive engine in a plane, rather you will more likely damage it from mis-using it, ie trying to force it to make power at an RPM where it was not intended (by using boost ;-)
The same applies for boats - automotive engines either rot, seize up from lack of use, or die from sustained full-power operation rather than actual "wear".
Raising boost to higher than recommended levels *should* bother you, unless it's a diesel, or you have had appropriate race-mods made to the engine, and its' internals strengthened.
Again, I expect certificated aircraft engines are a different story completely, and I have no knowledge of that.