So recent comments made me do some more research. Here is some more info in regards to the use of Iridium plugs...
per NGK engineers in regards to the use of fine wire in an Iridium plug, ...."because of its small size, can reduce the required coil voltage by as much as 20 percent. This means there an even greater reservoir of voltage at the coil if the cylinder requires it."
Fine wire plugs were designed for modern high mileage engines, the addition of precious metals to the center electrode was to increase durability.
NGK goes on to state.... " The move to iridium plugs could potentially be a performance advantage" Note they say "could' not "will".
Most modern ignition coils can provide more than enough voltage to fire the spark plugs; needed for higher compression ratios, various octane fuels, cylinder temps, etc. (This a my personal comment, not that of the NGK article I sourced).
I found this interesting in regards to heat/operating temperatures..."the addition of the precious metal portion of the center electrode contributes only a small amount of heat and is not a source of pre-ignition."
"Reeves (the Engineer quoted) emphasized that the heat range rating of a copper-core spark plug and an iridium plug will be the same and that it is the tip (overall) length of the center ceramic that determines any plug's actual heat range."
So not to beat a dead horse, I will close out this discussion with no further response. Thank you to those that responded! Good input!
In summary, my personal reason for considering Iridium plugs was strictly for the possibility of extended plug life and reducing service intervals to checking gap and plug inspection. I am a former auto mechanic so tearing the bike down to perform this function is not an issue. Instead of the Yamaha recommended 4000 miles (plug Inspection), 8000 miles (plug replacement), I would prefer that at the recommended mileage of 26,600 miles to check Valve Clearances at which time to also inspect Spark Plugs, check plug gaps and if needed, replace them.
Safe riding to all!