Good job, exactly what I would have done.

I never consider using above MFG spec a waste of money since, we tend to hold onto our machines longer than the usual. Seen so many problems that the engineers overlooked and guys out in the field had to deal with, so to me its a safety factor.
While the Iridium plugs may not provide a real seat of your pants major difference they do provide the longest service life and are easier on the coils. It has to do with the voltage to fire, which is usually lower and when wearing down does not stress the coils for extra voltage they were not designed for.
I have found quick fire ups and smoother idle with these plugs.