Who has an opinion on the comparison?

I've been riding my Nishiki Comp II with a Cyclone shifting group on a Campy 8spd cluster (12-25). I've got some Superbe and Superbe Pro derailleurs sitting pretty in my drawer. Would switching from the long cage Cyclone to the short cage Superbe Pro be:

an upgrade?
a downgrade?
negligible?

I tend to just ride with what's working and not always consider subtle improvements, but I'm easily swayed!