why are coppers better for the two?

I've heard alot of people on here say coppers are better then iridiums, but no one has explained why. Should I take my $40 plugs out and put coppers in? Ive only had them in there for 3,000 miles is it worth it to switch them now?

Copper is best for any car.
Copper is the best conductor of electricity.

The "problem" with copper is that it wears quickly.
Platinums will last longer at a slight cost of optimal performance. That is why the factory uses them.

I would use copper and change them every 3000 miles with your oil. They are only $1.75 (or os) each.

Iridiums are a terrible idea on a boosted car as the tiny electrode can break free and damage pistons, valves or both. This has happened on at least three turbo MR2s.

I've had an iridium stuck in my old head since i got the car, it would have done at LEAST 60,000 miles and hasn't fallen apart and was still working but has definately worn away a lot....

with my new head going on i'll be using copper plugs and changing them with every service. it makes it a lot less likely that a plug will get stuck again and means my engine will always have fresh good plugs without too much expense...

Thanks for the input, looks like I'll be taking my iridiums out as soon as weather permits.