If you do video you won't need AF.
Obviously you may prefer it for stills, perhaps fit a split prism focus screen to assist MF in stills mode?
Declicked aperture or electronic dial?
If video is going to form a big part of your work then a manual iris is great, and declicked even better. For video you get a live view of how things will look, you'll need to switch off exp comp in live view to get a true view for stills.
Obviously as you stop down the viewfinder / image darkens, you may prefer to compose and focus wide open and stop down before shooting - easy for video, pain in the a for stills, a bit 1960's.
But these are the compromises for a well sorted bright inexpensive prime.
Only bother with the cine version if you are absolutely going to use follow focus gearing and a rig. The photo version is cheaper and easier to live with for mixed use. And you can get a declicked non-cine version.
++ for this
Really the biggest advantages of the cine version is a declicked aperture control (which means you can change the aperture while filming with it being less noticeable), and I believe a much longer throw on the focusing ring, which is better for video, especially with a follow focus setup.
For stills, I'm assuming you are using some kind of strobe/speedlite lighting, right? So you're probably stopping down to f/8 or so anyway, so you can probably get away with your current focusing screen, but I believe the 6D has an officially user replaceable focus screen which means you can get a higher precision screen to more easily get the focus using a manual focus lens.