I see dark burnt colors in the DK2. For a split second, they are normal (like in viewport), and boom, they go darker. For me, it looks like everything goes darker when low persistance kicks in (it's just my guess, because in Unity 4, if low persistance is off, the colors are bright and go to "normal" when low persistance is on. So it looks like in this case they start normal, but when low persistance kicks in, they go super dark). Important thing - I see burn colors only in the Rift, on the display. If I make a screenshot - the colors are normal on other displays. The dark colors are visible only through the Rift.
Unity 5 beta 19 and 20 (tested both), Oculus 4.4 and 4.3 (tested both), firmware 2.12. Other demos look ok.