The line of light cruisers were always meant to be slight alterations to the class in order to emphasis styles of play. The Artemis was the core model on which the light cruisers were based. The Apollo emphasised beams slightly and the valkyrie longer ranges. Since their firat design, I am not sure how much the emphasis has changed. Fundamentally though, they were light cruisers that could fulfil a general light cruiser role first, with slight specialism second.