You see, this is a misconception. NO compromise need be made between gameplay and history. Why do people think that making something historically accurate means poor gameplay? It doesn't have to! Making the start positions, factions, and units of the main campaign more accurate can mean (and does, for EB) making them incredibly diverse, flexible, and add even more gameplay elements than not.
There´s one difference, though. You´re a modding group who can take all the time you want to and you don´t (need to) sell it, neither to a publisher nor to the final customers. You don´t have to pay wages to your people, raise funds, finance the tools (what´s a copy of 3ds max? About 5000$ ? And that´s just one of the tools you´ll need). You don´t need to worry about it flopping due to lack of interest. You don´t have a publisher who´s making quite an effort of promotion and expects it to pay off... Do I need to go on?