Endeavors, Endurances and Defiants fit into a very strange and very fun niche in the Imperial Navy.
Where the Dauntless functions essentially as a huge escort craft, the EED crew serve as smaller versions of larger ships, namely the gothic, dominator and Dominion.
This essentially means that they serve two functions:Replace the standard cruisers and increase battle cruisers on the table, setting the stage for the Armageddon battlecruiser and it's absurd firepower.
Just realize that they do not function well with escorts, but function great with other standard cruisers, providing turret support and extra firepower to your normal cruisers.