Yes yes yes. Supprisingly everyone on the net wants to get a swat on whats been done in finding nemo and sharks tale.
But see idea particle and copy dont mix all that well the idea of particles is to simplify things to movement particles that sufficently accurately represent whats going on.
Instances too are siplifications where a single shape shares the properties of another shape. Saving memory.
A copy however has all of that data, so why would it need the particles for anything? Its just extra data for the computer, after al why have that data there 2 times? If you wnat objects skip particles.
Okay now i can see that there are a few conditions where it could be usefull to do but a example where its NOT usefull is if you first make object live than click particles on the object and now copy objects in the particle positions, INSTEAD use scriprt paint tool! It comes along witha scrip that allowa you to paint copies even randomized ones on top of any surface, or use a animated snapshot.
A example where it IS usefull, imagine a pack of robots that need to bbehave differently, and need a manipulator of sme sort for the result thats easy to codinate. NOW a particle copier is of use, its just a easy expression coupled with mel. But its better to not create objects on fly but instead bake the results on objects.