Feel free to disagree, but I ran them in the wagon for a couple years...they work awesome and last for friggin' ever. They're like a durable racing plug.
Small electrodes work better...it's just physics. If you can find a copper plug with a small electrode, maybe it might work better, but I haven't seen those anywhere.
3000 miles is a lot for a plug????? I guess for a copper, it's a 20% of the life, but for a platinum or iridium plug, it's only 3%.
One (big ignition) company I know ran a durabilty test on thre iridiums on a blown motor with a mag on the dyno. They never wore them out, they said the plug was good until the resistor burned out(>5Kohm). They were quite enthusiastic about them...they take less voltage to fire...so you could actually open the gap if you wanted to, all other things held constant.