I disagree on your statement that the 6D is a great 2nd body for pros
if you shoot a 1D or 5D3 then the 6D ergonimics and AF make it a total non starter
i notice you put in some mythical cameras in the list including a 6DII not really sure why you did this
if the 6D ergonomics and af a fine for a particular persons pro use then they would be far better served having 2 6D bodies rather than mixing the egonomics up as they are vastly different having a 5D3 or 1D and a 6D would just be a PITA IMO even the 5Dmk2 is better in this regard than the 6D even though the 6D is superior in many ways
when under the pump being able to do things fast without messing around is key and having similar ergonomics on all bodies is very important to achieve this
I included "mythical" bodies because they represent logical progressions along each line that would make sense in unifying the upgrade paths and making them much more coherent. The 7D Mk.II is still speculative in terms of what it will be able to do, the 6D Mk.II obviously is just a dream at this point, but they represent what could be included in these line ups to really bring each category together. Same with an APS mirrorless. The 7D Mk.II represents a premium APS-C Prosumer body and falls in line as an APS-C 2nd body capable of performing professional duties. The 6D Mk.II represents a premium APS Prosumer body and falls in line as an APS 2nd body capable of performing professional duties.
I didn't say the 6D is a good second body for pros, in fact, I feel the exact opposite. The 6D represents a huge failure in the Prosumer lineup in regards to an upgrade path. I actually feel kind of bad about how hard I've come down on the 6D, but that's probably because I really wanted it to be more than it was. It's failures were what actually prompted me to write everything up in the first place.
"6D Mk.II – N/A ($1899.99) – Advanced Prosumer APS. Great 2nd body for Pros."
sorry I was applying your statement to the 6DII to the 6D
but what makes you think they will give a 6D2 better AF?
they might upgrade it to 60D AF