Sounds like very good news, wonderspark!
I was also quite impressed when I read the specs of this little baby and wanted to try it.
Just a few days ago, I saw a video in which people were testing it with a Nikon D800 and had some rather disappointing results:
Click here
They are saying that the ninja was crushing the blacks so deep that you couldn't get any information out of them anymore. That would be kind of a dealbreaker for me, since color correction is most prone to problems in very low light setups anyways. And if the 4:2:2 color sampling is not helping because of the lack of information in the dark areas, that would be a problem.
I have to say though that they were recording with a DSLR. And I get the feeling that maybe this DSLR camera's HDMI output is made for image control on an external monitor, not for recording out of it. I can see how the camera will then not try to output the flattest color profile possible out of that HDMI port but an image that would look nice on screen, maybe even with higher contrast.
As I said, it might not be an issue with your cameras, but be aware of that and actually try it out when you get the thing, so you can send it back if the quality suffers...