Kolaches
They switched from the K2 Pro to the Canon. K2 Pro produces a more realistic image with the iZugar lens but at only 5K or 6k at 60fps.
Canon shoots 8K 60fps but its default IPD sucks (60mm). The Canon hack SLR implemented recently seems to make it a bit better but it's still not as crisp as their K2 production.
For what its worth, it's a difficult decision to make (considering the cost and time investment involved).
I personally love the image from the K2 Pro and would be happy to wait for SLR to fine tune their Canon hack till they get a tack sharp image (it's like 85% almost there, maybe needs a couple more tweaks).
Unfortunately, there are barely any cameras that can do 8k 60fps natively (only Canon and FM Duo at the moment, the newer Calf camera can't achieve 8k 60fps either).
Most of the other studios seem to be using upscaled, high-bitrate footage from the K2 Pro; use the FM Duo; or have a custom, dual cinema camera rig.