dwill23: My experience with the Sigma 35 f1.4 ART and 50mm f1.4 ART and 18-35mm f1.8 ART is that it's Impossible to focus consistently on Canon bodies unless you use live-view and have dual pixel AF. Then it's 100% ultra accurate, altho slower shooting.
Using live view means you don't get to hold your camera as steady as you normally would, and the camera never shoots as fast. Sold my sigma 35mm for the new canon 35mm. same quality, but way better AF accuracy, and $700 more, which was well worth getting perfect shots.
Granted sigma is on a roll, but they should fix the AF problems. No the DOCK does not help all that much. Even if you get it perfect it will still be inconsistent which is very well documented online.
My 18-35 ART focuses beautifully with no finetune adjustment needed on both of my D7200 bodies. It didn't with either of my D7000 bodies, though. Perhaps there's something in the newer cameras that leads to more reliable autofocus? More cross type sensors, perhaps? Who knows...
On the other hand, my sister rented an 18-35 from lensrentals for her XSi Rebel and found it to be unusable because the AF hunted constantly all the time.