In war armies should be out attacking all the time so any advantage that elf has oow with total defence is gone/irrelevant. unless the elf keeps his elites home and not attack which is self defeating then elf will have less army 6/5 than DE 6/6 (both have same population). in the beginning of the war DE has advantage. I think in short wars DE will win. Long wars are another story with the -50% Combat Losses and depends greatly on the leadership of the warring kingdoms.