Yes Dave, that is worth mentioning. The MF arc is short on the Sigma. That is probably also why the AF speed is so close to the Canon as it is. It could also be an cause for less precise AF, but I have not noticed that as a problem. If it was an 85mm 1.4 lens it probably would.
Your observation that I don´t have a TS lens at the moment is correct. I bought the 24mm f3.5L TS II when it was released, but ended up selling it because i did not use it enough. But of course, as soon as I sold it I had a number of situations where I wish I still had it. It may well be that I buy it again. I have had the same history with the 85mm f1.2L. The one I have now is No.3. The AF on the previous bodys I have used (5D, 5DII, 1DsII and 1DsIII) simply was not accurate enough, so I was constantly irritated that I had ears or noses in focus and eyes out of focus. But the (spot) AF performance of the 5DIII and the 1DX is in a different league. But the very shallow depth of field still makes that lens a challenge.
Steve, with the Zeiss, do you find it sufficient to rely on the AF indicator in the camera viewer, or do you use live view with magnification?