I've been experimenting with the relatively new 2K option for a series of TV spots I've got coming up. I'm choosing 2K to (hopefully) intercut better with my Black Magic Pocket cameras, which record in ProRes 422 HQ 10 bit. I have some questions because - typical of JVC - there is virtually NO documentation on this option.

One of two options when choosing 2K is 422 - UHD doesn't have this ability. Is this truly a 422 color space?

Why, when setting to 2k, is the time left on cards identical to shooting in 1080p? One reason might be it's locked at 23.97 (or 24fps) and I've been shooting 30p in HD - and they're both 50mbps - but still it seems odd.

In 2K the VSM Prime Zoom feature acts identically to when shooting in HD. Does that mean 2K is mapping a significantly smaller area of the sensor than 2K?

My visual tests - which admittedly lack any scientific control - are quite good, stunning actually - noticeably better than 1080 in some situations. When laid into a ProResHQ timeline there is a small letterbox, which is fine because I'm letterboxing the spots anyway, but it also seems the 8 bit image grades more easily, more like the Pocket's ProRes.

Has anyone else (like Steve Mullen) experimented with this setting? And if so, have you found any pitfalls?

2K is 1080HD with some extra vertical resolution. The camera is essentially shooting the same as HD video.

As the codec is exactly the same as when you shoot in HD it's normal the time left on your card is identical, also as the only difference is that you add some extra resolution this should not make any difference when you match it up with your pocketcam compared to shooting in HD.
Can I ask in which situations C2K is noticeable better then HD?

What I've been doing is shooting things that tend to exhibit artifacts, especially when adding FilmConvert, comparing footage from the Pocket Cameras (which are very clean) and the 8 bit JVC, which can occasionally exhibit latent macro-blocking - as all 8 bit cameras do,

For instance when shooting against a solid background, like a wall that has a variation in texture and shading, it seems that the 2K provides a cleaner rendition - I can push the grade more easily. Admittedly it may be my imagination because my eyes are getting tired doing this.