I appreciate the good data!
Since the P Mag installation manual strongly recommends changing any automotive plug after 100 hours, I will go with the standard copper plugs this time. Maybe next swap I will try the iridium plugs and do a back to back comparison trying to gather my own data.
Good point about the GAMI spread. My assumption which I failed to mention was that it is low enough so as to be no factor. Mine is about 0.2-0.3. 0.0 is very impressive.