I believe Enya and OS use pure platinum in their glow elements where Fox and K&B use an alloy of platinum and rhodium. If the plug has pure platinum in it, the catylic reaction with the methanol will be much improved. Also it will allow the plug to last longer under normal use.
Adding rhodium to the element is supposed to be an improvement. OS uses it also, it helps to keep the plug hot during idle. It also makes the element stronger. If I correctly recall, older pure platinum plugs were more likely to break from vibration.