The only problem is.... If you mix with headphones as flat as the AKG's, then the sound produced will inevitably sound dark on most other hp's. There is neutral frequency wise - i.e graphs. But there is also neutral in how we actually hear music. Live music. And there is no one here going to persuade me that the AKG K/Q sound realistic. The HD800's on the other hand, have given me the most realistic presentation I've heard yet.
Actually it is quite the opposite. Mixing on a bright headphone will lead to a dark sounding mix and vice-versa.