Now only historical interest:
EK did produce a film that had a distinctly different mask a few years ago: Primetime 5620 640T. It was unprintable, unless you wanted a weird, muddy mess. It was intended for direct transfer to video so the colour could be taked care of during transfer. For the time it was a high speed film with comparatively low graininess. Unfortunately the radical nature of the film caused problems for colourists (the guys who transfer film to video) and it never really stood a chance. I was involved in the field tests in a small way, and made a short with it - entirely at f/1 and 16⅔ fps (that's 50/3: three fields per film frame at 25 fps PAL, slightly jerky). EK made sure that the transfer was a good one and I was happy with the result.
Even by modern standards it was not grainy. See the two curves below. One for 5229 Vision2 Expression 500T and one for 5620. Note how the sensitometric curves for 5620 do not have the typical RGB separation (indicating the mask colour) that most colour neg films have - typified by 5229. Also notice how shallow the curve is compared to 5229, which isn't a contrasty film. The lower contrast gives a slightly false graininess comparison: if the contrast of the 5620 has to be increased to give a good image, the advantage is lost. You had to light for it. That didn't help its reputation.
Best,
Helen