I can't imagine how it would ruin airflow really. Although my CPU temps have gone up a bit but that's because of the way the H80's radiator is placed now.
In my old 800D case the radiator fans were sucking in cool air from the back of the case, and with the Raven the radiator is sucking in air from inside the case itself.
My GPU temps have gone down quite a bit, around 10c.