“No halo. Even on a DVX-100. Isn’t that interesting?”
Please. You are being highly disingenuous .
That is, as you mentioned, a grab from the now defunct Rel-Stream modification to the DVX-100, which has absolutely NO bearing on this discussion at all.
The HVX at DVCProHD and DV50 has exactly the same color space as a Digital Betacam camera: 4:2:2
I any many other have pulled fantastic keys shooting on properly lit green screens.
However, I think you may be asking for too much from a 1/3″ chip camera.