Yes, this is why I'm asking here. I had a 5D mk2 which I used only for Aurora Borealis and landscapes. I found the autofocus and 3.8 frame rate to be serious limitations for the kind of shooting I do. I think I could live with a 1.3 crop 16mp camera if the autofocus performs on par with the 7D2. With birds its all about the keeper rate and I want to have this camera for a few years.
Well, there is no easy answer. My 7DM2 is slightly soft and has been 2 Canon twice. I prefer the 7Dm2 for a few reasons, The Af is quicker to acquire and seemingly better tracking. Once you get the focus cases (derived from the 1dx) and focus points figured out it performs very well. I came from the Nikon D800 and D7100 and for someone earlier in the thread that mockingly said the D7200, the ISO performance is not such a big deal as everyone makes it to be. By ISO 400 they perform very similar in terms of noise, and that is where we really shoot with BIF anyways.
I really had no plans on getting the 1D4, here is the little story about it..
Added a little more magic bird dust to pile today. | Photography Forum Af performance is still very good, but one thing that drives me nuts is I can't use EC in manual mode with auto-iso. The Af system is far simpler, so in a way it is a good thing. Pretty much 1,3,8 or all focus points. Noise performance is a touch better than the 7dm2, but if you normalize the results and view the 7dm2 at say 50% instead of 100% the results are pretty similar..
A few other thoughts. The 7dm2 seems a bit more customizable with the buttons. I was a pure BBF guy with Nikon, but I actually switched to Front focus with Canon because I could program the AF-on button to 1 shot. The 7dM2 shutter is much quieter than the 1d4, and I mean MUCH!
Now, with all that said the 7dm2 has been my go to camera, but lately I've found myself picking the 1D4 more often. I think because the 7dm2 is slightly "soft" (and it has been back to Canon twice) the 1D4 produces better images in real life. On line you will see a split of what I am saying where some sold their 1d4 after getting the 7dm2 and others couldn't get rid of the 7dm2 fast enough and kept the 1d4. It almost seems to be a bit of a lottery with the 1d4. I have tons of images, so if you want any raws, let me know...
Here is ISO 8000 on the 1d4.
The Return of George! 10_27 1 by
Kristofer Rowe, on Flickr
Here is a 6400 from the 7dm2 (500 f4+1.4x)
Cormorant High ISO 9_13 by
Kristofer Rowe, on Flickr