In Crysis the "very high” settings had been DirectX 10 exclusive. In Crysis Warhead this has been changed.
Crysis Warhead: No more special DirectX 10 effects
As we interviewed Bernd Diemer, the producer of Crysis Warhead, he confirmed that the "very High” settings are renamed to "Enthusiast” and will be available for DirectX 9, too.
Bernd Diemer: If the system can display it, because it has the performance, this is right. http://www.pcgameshardware.com/aid,653869/News/Crysis_Warhead_No_more_special_DirectX_10_effects/
Crysis Warhead: No more special DirectX 10 effects
As we interviewed Bernd Diemer, the producer of Crysis Warhead, he confirmed that the "very High” settings are renamed to "Enthusiast” and will be available for DirectX 9, too.
Bernd Diemer: The former "very high2 settings are now called "enthusiast” and this option is now available for DX9, too. We removed this exclusiveness and thought: If people want to run this on their system, why should we restrict it?
PCGH: So there are no visual differences between the DX9 and DX10 version anymore? Bernd Diemer: If the system can display it, because it has the performance, this is right.