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I've been in favor of a rotating facet concept where you had the event on Tokuno for a certain period of time, then Ilshenar, then Trammel, then Malas, then Felucca, repeat or switch up. In the process, have a set of dyes that are unique to each facet (i.e. original Tokuno Dyes for Tokuno, ToT 2 dyes (aka original metal hues) for Felucca, the current metal hues (Dull Copper, Shadow, Copper, Bronze, Gold, Agapite, Verite, Valorite) for Trammel, ToT 3 dyes for Ilshenar and a new set for Malas), then tweak the other item rewards on occasion.
Again, the biggest problem to this remains the size of the dev team and ability to keep it updated.