We do know that the OEM plug uses different electrode material, as I stated earlier. Ed
Are you concerned that iridium and platinum might have different electrical characteristics? Generally I'm in favor of using OEM replacement parts but the cost difference is enough that it may pay off to find a suitable replacement. If it didn't work as well you could be sure it would manifest itself with lower mpg or other symptoms. It's interesting the Denso plug uses a different precious metal for each electrode. I wonder if platinum is more resistant to erosion when used as the ground electrode?