There are lots of custom features on the 1D bodies that once you use them you will not want to live without them like metering tied to AF point, and the ability to set a aperture range when in AV and and a SS range in TV plus others. Not to mention the AF speed an the stellar ability to drive AF the fastest of any Canon bodies. I have my 7D as a backup and when very reach limited or when a smaller lighter body is the best choice or when I need to shoot with 2 bodies. I have had no problem PP the higher ISO shots in LR4 and CS6. I do prefer the 1D4 files but the 7D files give less leeway if you under expose. In really crappy light the 1D4 is my choice.
Yeah, I was going to mention those things in post but decided to to keep it shorter.
I've been shooting it with linked metering and set up all min/max, but left them disabled while testing it out. Since my 300 will live on this body, I'm about saving different sets for with and without TC's.
The 1DIV seemed to lock focus quicker than the 5dIII when i was shooting ducks at the pond that had just taken flight. I was even able track some small fast bird flying about the water that even at 100% crop doesn't file the frame.
I also tried using 45 point expansion while shooting some Hawks and Vultures in flight and liked how I could see which point it was using to AF.
I haven't tried pushing the ISO yet but from the head to head comparison I saw of it and the 5dIII it looks to be right there with it so it will definitely make me a lot happier than the 7D ever could when shooting motorsports at night and wildlife in low light.
Also it's 1.3 crop won't be so bad to use with my EF lenses if my 5dIII is out for service or broken.
I'm still curious about what the 7DII will bring to the table but unless it's a game changer I'm no longer planning on buying it like I was before I got my 1DIV.