Varies with dragon types. Melee specialists bite harder than Requiem's, mage types - less.
I'm pretty certain even melee specialist dragons deal quite a bit less damage in EMD than dragons in general do in Requiem.
In fact I've just checked the exact values to be sure:
Requiem dragons have 350 unarmed damage racial.
EMD dragons have vanilla's 25 + individual bonuses that may be as high as 250 and as low as, I think, 80.
275 is nice output but still much less than 350, while 115 is something even an unproficient character can achieve with a daedric mace - a dragon bite or tree trunk sized tail to the face should hurt more than that by default.
That's pretty vague. I can say the same for EMD.
EMD goes a long way making fights more interesting but giving dragons unique abilities and combat styles, true, but in the end an individual dragon will have the same predictable combat pattern as in vanilla, will become predictably grounded at fixed HP percentage and so on.
OTOH DCO keeps you on your toes by randomizing those patterns, randomizing injury effects, adding end of battle scenarios to try and tip the scales in dragon's favor should you be winning and generally making dragons more of assholes in battle.
I'm not dissing EMD, having played a lot with it and really loving most of its features and patch allowing both to be used with Requiem would be one of the best things ever, but if I do have to choose my pick is DCO.
The ground isn't a trampoline and dragons don't actually have jet engines. Those ragdolling shenanigans are as retarded as 5 meter "giants" sending you flying by stomping the ground.
Dragons may not have jet engines, but they send sufficient masses of air hurtling at sufficient speed by flapping their wings to hurl *their own* bodies up into the air - guess what will happen when such a mass of air hits you in the face which is guaranteed when a dragon takes off or lands right next to you?
This means DCO rectifies one of the main ways dragon fights felt very wrong on a very fundamental level in vanilla. That's a big plus.