I was in a similar position not too long ago. I mostly shot landscapes with the occasional sports/action stuff. In the past, the only wildlife I shot was basically to pass time waiting for the sun to set for my landscape. Recently, I've started to do a lot more shooting, mostly birds, and felt additional speed would be a huge benefit. Already shooting a 5DS I didn't expect much in the way of reach (as the two cameras crop down to effectively the same size), but I can say the 7D2's 1.6 crop does mentally help me if not actually as well. The final factor.. at least between whether to get a 80D or a 7D2 was the 80D's size and fit in hand. I didn't like the feel in hand so I chose the 7D2. The differences in DR at 100 or 200 probably would make a fair bit of difference, but considering this camera was probably going to live at ISO 400 and higher pushed the edge back to the old sensor's high ISO performance weighting. I just don't see myself shooting at 100-200 ISO... the light will be either too harsh, or the shutter speeds will be too low for the subjects this camera is made for. I didn't weigh the articulating screen into my decision, only because I don't really like 'em, but I know they have a real tangible value. The 80D's 27 point F8 AF capability was very enticing until I read that there were only a few lens/extender combos that it actually works with.
Regarding whether or not a crop camera has value for you, I'd assume the crop difference would be pretty substantial and worthwhile but only if you plan to keep both. I can't see a reason to dissuade you from it if both fill your needs. If you are planning to keep only one that a tougher question, as I would probably choose the FF.
As for whether to go 80D or 7D2, your scenario appears a little more biased toward the 80D. It sounds as though the touch screen and resolution edge may benefit you more than the additional 3 fps and AF System.
Good luck sort all of these feature and needs out.
Thanks. It's not easy to choose.
What I would gain with 7D2 when compared to 5D3 (which I will keep) is more fps in silent mode (4 vs 3). This might bigger factor than it sounds. I use silent mode as much as I can and 3fps is just really slow when animals are moving. 80D offers same 3 fps as 5D3.
The 7D2 has also virtually same controls as 5D3 does so switching between bodies is really easy. AF functions are practically same and both has customizable use cases for AI-servo.
The big downside is lack of touch screen and articulating screen. However I must admit that I am not 100% do I really need tilting screen. In macro work it would be really nice and probably it would give lot of help when photographing reptiles.
Which is more important? Ergonomics of controls or tilting touch screen?