My biggest frustration with the current AF-C implementation is the (apparent) total lack of z motion compensation. To me, it appears that AF-C is just an auto-refresh version of AF-S. If the subject is moving towards the camera with the focus point confirmed and you fully press shutter release, it seems to wait to get another focus confirmation - fixes the focus of the lens, mirror moves, shutter moves, subjects moved...
It also appears to take longer to get focus confirmation, compared with AF-S.
There are work-arounds; pre-focus and wait, or use a small aperture and gains some depth of field to hide the problem. Neither is great for wild-life or the 'really-must-get' bride walking towards camera shots.
Because I find AF-S very accurate, even with the F1.4, pupil only in focus shot, I don't think Pentax have a problem with the focus sensing accuracy. What has been missing is the ability to process that information quickly enough to follow focus trend/subject motion.
The K
NEW that was displayed last year visually appeared to have a different, larger, PDAF module. There is no way to visually determine changes to the processing capability on the inside, but it not unreasonable to expect that progress with the GRiii platform change to an Android based OS will have opened up many more options for processing hardware for the K
NEW. All this (probable) new hardware is nothing without the appropriate software. I suspect that this is the main reason for the long delay between showing an apparently finished camera (hardware) and having something to sell (complete hardware/software solution).
I expect we will all (well most of us) be impressed with the end result, when it arrives.