But, 4:4:4 RGB is clearly better than 4:2:2 YCbCr (right?), so people have been very interested in this capability.
Now comes Philip Johnston from HD Warrior, who has managed to get an actual reply from his contacts at Sony UK, and they have added new details to the story. The really important part is this:
...the data of the image created by the FS100/NX70 processor is just 4:2:2.That's right, even if you have a display device or a recorder that supported RGB 4:4:4, the signal you are getting from the NEX-FS100 is just the 4:2:2 signal, converted to 4:4:4. So really, there's no reason to worry about this format at all; as Sony notes, the camera simply outputs it if the device that it is connected to supports that protocol.
Then it is lifted up to 4:4:4 in the HDMI processor if the connected device is 444 capable.
So you can cancel your order for the Sony SR-R1 digital recorder (the only digital recorder I know of that claims to support 4:4:4 RGB) if that was the reason you were buying one! You might as well just stick to the Key Pro Mini or the Ninja!
HD Warrior: SONY UK deliver amazing news about the FS100 and NX70
NOTE: If you've never quite understood color sub-sampling and the differences between 4:2:0, 4:2:2 and 4:2:2, then read this post from Andy Shipsides at CineTechnica: HD Formats: Color Model & Color Sub-Sampling
SetaFilms: Report from CineGear – FS100 does 4:4:4
Cinema5D: Doug Jensen says FS100 hdmi is 4:4:4
Vimeo: Sony FS100 with Juan Martinez from Sony
ProVideoCoalition: Untapped features in Sony NXCAM’s new HDMI output