luminol reaction

[hermanntrude]

OK so I got my luminol today and I've been reading various demonstration sheets across the interwebz and seen that people use various different combinations of oxidiser and catalyst.

 

So i've read that you can use Fe2+ or Cu2+ or other metal ions to catalyse the reaction, but potassium ferricyanide seems to be a popular choice. My question is this: why bother to use such an elaborate compound when copper sulfate works just as well and costs a fraction of the price? I've got both and i'd like to find out why people choose one over the other in case it'll save me time trying both of them out.