I am just going to relate my story.
I had platinums with 50K on 'em.
I switched to Autolite copper core plugs (764s, IIRC) , and the motor was much happier.
Your mileage may vary (YMMV) Just in my case, and I have had this car since new, but yes, for my car, these copper core plugs made the engine run better.