I've been shooting with 1D Mark IV's since the day they announced it and it's still one of my primary camera bodies. It virtually lives on my 500mm f4L IS II +1.4x, and it continues to deliver incredible images...
That said, I picked up a 7DII several years ago to get a tad more reach and I've been through 3 of them because of AF issues... this third one though seems to be fine. The camera is more technically advanced to be sure, with many more ways to get yourself in trouble with the myriad numbers of controls and settings it offers. I would highly recommend starting out shooting with the default settings until you get a feel for how it operates.
I find "Case" settings to be confusing at best, but do agree with Dave that you need to work with all of them to see how they perform best for you. I've found that the default case 1 to be the most versatile. Since you do have the option to customize the settings, you may ultimately end up modifying one of the other "cases" to work best for you.
Good luck!