Rewards should be equalized (Rifter and Retriever give pretty much the same amount of EM related to ship price). Instead there should be L1 to L4/5 Paragon agents that offer a higher investment/higher reward structure. This would include trading in Battleships and maybe even bigger. The idea of having this as a sink is good, but the implementation is bad.
To be an actual, effective sink, EM should be used to rent cosmetics on a “per asset” base, not buy once for a certain type. This would scale well with bigger corps as they have more structures.
Corps could have an EM wallet each member can donate to. This way, maintaining corp level cosmetics (structures) would become a collaborative task.
Also: why make yet another currency and not just use Paragon LP. Evermarks have no extra value over using LP. Or do they? No, i do not consider “clutter up my wallet window even more” an extra value.