I have a Sony AX- 100. I record in XAVC-S 4 K and a low resolution file. This because I can import 4K in Premiere but my computer is too slow show it real time. I edit the low resolution film 1280 x 720 on in a sequence of 1920 x 1080 and adapt all the files to the resolution of the timeline ( all Pal NTSC my be a little different) and when I am satified I simple change all the files for the high resolution one( by changing the name of the directory ) and export my movie for blue ray.
It would be nice if you could export it to Pro res for the Cinema but at my studio I cannot see 4 K in full resolution so it has no use ( yet).
I use a PC with Window 8.1 and Premiere Pro CS6