my experiences of them are using them on 200sx's. A few friends had them destroy sets of Forged pistons. We always ran NGK copper core plugs becuase of it (BCPR7ES usually) as they're bomb proof.
Most of the reason people have trouble with different plugs in clios is using Bosch ones, which are usually non resistor plugs so the coil is overloaded. The 200sx had 2 plugs recommended, a PFR6E-10 for cat equiped cars, or a BCPR6ES for non cat cars. They're interchangeable. I'd run coppers in my own clio happily, and have done in some friends cars with their knowledge with no issues, they just have a shorter change interval and need the gaps adjusting