I have Tokina SD 400/5.6 AF (exactly the same as in the first photo).
I acquired this one cheaply for experiments. These Tokinas are known to be prone to lens separation, but mine has another problem- some kind of foggy substance on one surface, which I managed to clean, but the surface of lens is damaged a bit and the lens looses a bit of contrast.
I had to open the lens for several times during my repairs and can say it's built to the best Tokina standarts (except for lens glue which is unfortunately "Tokina standard", too). Metal only, no plastic (except for collars and mount contact holder), extremely easy to disassemble and assemble, highly modular construction. It is clearly seen that the front part with all the glass is one unit and the rear part with focus drive and aperture control is screwed on. There is even place in lens frame to install AF motor (for Canon version, I suppose).
Other problem on my lens was aperture control from camera (setting at 6.3 aperture won't close at all, setting at f:8 it just closed to appr.1/3 stop, at f:9 it would close to about f:6.3). It was super-easy repair (unscrew bayonet mount, loosen 2 screws on aperture activating lever, ajust, tighten, screw back mount, check on the camera). Now aperture works OK.
The lens itself is small and light (for all-metal 400mm prime), it can be hand-holded for prolonged time with no problems. AF is frightening fast on K-3, with loud metallic "clang" at the end stops, very reliable in general. Image quality is not premium, but not that bad at all, too. The biggest issue is purple fringing that can be very obtrusive, so it is better to shoot RAW (PF is generally easily removed in RAW converters). With good light and good focus even 1:1 crops are useable.
I don't have many examples from my Tokina because I repaired it in October? and we have total 24/7 for the whole automn/winter period. Most my shots are about F5.6, ISO3200, 1/250-1/125, so documentary only
Few examples that are somewhat useable:
Heavily cropped images at high ISO's
Lightly cropped, IIRC
With a flash at reasonable distance (so lightly cropped or not cropped) and lower ISOs