I posted the 1d iv was better at high ISO/ pushing an image 1-3 stops over the 7d2. I still stand by that from my real world experiences.
The 7d2 has a sharper lcd screen, in theory better af (but that can be a mixed bag), better video, better silent shutter, takes sdxc cards and can read sd cards much faster than other canon cameras...more later, super tired going to bed.
Better video? I've shot video with the 70d and the 1dIV and the latter looks much better. Better video AF? Better 60p frame rate? You betcha. But not better output quality. I've yet to see any 7d II video look great at all. Anywhere. Just something off, like the 70d. Muted, low contrast, etc.
I love my IDIV, and love having the metering tied to the AF point. I use the center AF and it tracks great, built-in grip, and considering I picked up a 136k "miles" unit, it was about $1400 with 2 batteries. Don't know how fast or slow it moves a 600mm lens as the 300 2.8 is the longest I use. For 9u baseball, the 1div + 70-200 II is really all I need...
All I can say is having just picked up a 1DMKIV, I'm very impressed with the 7D2, especially considering the original prices of each.
The other thing besides image quality is the weight, even the 100-400 which I don't consider super heavy combined with the 1DMKIV, makes for a rather heavy combination.
One which on a recent trip brought on an attcck of Sciatica, which made the trip rather painful to say the least.
Both really great cameras, but I might like to try the 7d2 down the road.