Many thanks for posting these high ISO crops from RAW.
They are the first I've seen.
I've just compared with 5DII shots taken at ISO 3200 and ISO 6400 both put through LR4 using the same settings.
The ISO 6400 results are pretty close in terms of visible noise and retention of fine detail.
Arguably at ISO 6400 the 5DII shots have the edge, but it is close.
The results back up what everyone has been saying....
The 5DIII has getting on for two stop less noise at high ISO.
I know I can produce an acceptable A3 print from the 5DII at ISO 3200 with no luminance noise reduction and default chroma (25/50). Not perfect, but good enough to sell in a gallery.
It's possible that the 5DIII may be able to produce an acceptable A3 print at ISO 12800.
Could post some samples please so I can check