I can't understand what all the fuss is about. Edmund has posted an ISO 800 image on another current thread, 'High ISO versus Underexposure' at http://luminous-landscape.com/forum/index....pic=20997&st=40
where it is demonstrated that the image showing banding and striations in the shadows, as well as a lot of noise, is in fact drastically underexposed.
The only uncertainty in my mind is the degree to which the image is underexposed. My estimate from ACR is 1.7 stops. Others seem to think it's as much as 4 stops. Whether it's 4 stops underexposed or only 1.7 stops underexposed, I would say an additional 1.7 stops of exposure would have been sufficient to remove that banding and a lot of the noise.
If you want a film-like texture, wouldn't it be better to expose correctly in the first place and then add grain later in Photoshop.
Banding, striations and heavy noise are always a consequence of underexposure when the scene has a fairly high dynamic range, whatever the ISO, in my experience at least.
If I take a shot of a sunset with my Canon 5D at ISO 100 and neglect to give a full exposure to the right, I'll likely get very ugly banding in the deepest shadows.