I wish the 1DX could change crop factor like Nikon.+1
Why? There are only 3 positives I see to the variable crop factor.
1. Nikon cameras FF cameras can take crop lenses from Nikon. But Canon FF can take crop lenses from 3rd pard companies. Are there really any Canon crop lenses you need to have but can't replace with a Sigma, or Tokina?
2. You save space on the memory card. With 32,64, and 128GB cards under $100, is this really still an issue?
3. I don't have to crop as much in post. SO what, a little more work. What about the photos that are saved because your subject is off center and not cutoff by the frame?
Not trying to argue here, but I like the crop factor of cameras that cram more pixels into a smaller space when I need more reach fro a telephoto lens. But an 18MP 1DX photo cropped in software to Canon's 1.6X factor is a 7MP photo. Same in camera as if it was done in post. Only difference is in post I can move my 7MP around, or crop less or not at all.
If you are moving from crop to FF, losing a lens or 2 is a bitter pill to swallow, but hey.
My images go straight from the camera to my viewing stations to sell to my customers onsite. No post processing done at all, unless prints are bought. Digital sales are done onsite via USB flash drives. So getting it right in the camera is of paramount importance. Additional, selected images are sent straight to multiple 46" monitors, or at bigger competitions projected onto 20' screens on either side of the stage. Appropriately cropping in camera makes a much bigger impression on the customers when viewing on either the viewing stations or slideshow screens. With the Nikon bodies you can program a button to change crop mode on the fly. When I owned a D3S I learned how to do this as effectively as zooming the zoom ring.
Finally, I never shoot these events at full resolution or using RAW. With several shooters, shooting up to 600 competitors/day, we can easily take 100,000 images over a weekend. 8-12 megapixel is more than enough for what we need.