I'm not going to start a spark plug debate, but I did a little looking and I think I'll be fine with my iridium plugs even though OEM's were platinum.
"Until recently Platinum was considered the best material to use on the top of an electrode of the sparkplug, because of its durability. How ever Iridium is 6 times harder, 8 times stronger and has a melting point of 1200 degrees higher than Platinum. Put that into a harsh environment such as an engine piston chamber and you have a spark plug that can resist wear much better than Platinum. Iridium is one of the most unique minerals known to man."
Here's a link to the above article.
http://ezinearticles.com/?Iridium-Spark-Plug&id=101054
I realize this is just one man's opine, but since I have installed them, I'll just keep on truckin'!!
Thanks again,
dkf