I understand your point of view, and it applies to others as well, including myself. As an amateur, I think that one should master most functions of their camera before upgrading. Especially going from a crop sensor to a full frame. Full frame photography is far more expensive as a hobby or as a professional. You can buy 2 DX lenses or more, compared to one FX lens. I remember when the D700 and D90 were released, around 2008. The D700 came with almost the same excitement as the D850. And it came with a whopping 12.1 megapixels. Nine years later, we're at 46 megapixels, plus many other new features. And a camera that recently had a first ever perfect score of 100. That is indeed an upgrade. For some or not for some?

The advantages the 7DII, and most other current crop sensors have over the 1DXII for wildlife, BIF, etc is in the crop factor and the resulting angle of view. That and better image quality when cropping are important factors. Pixel density of the sensor makes a big difference. My 7DII has 20mp. My 5DIV has 30mp. Uncropped, give me the 5DIV every time, but if I crop the 5DIV image to replicate the coverage of the 7DII the IQ drops off noticeably. If I crop the 7DII shot, such as you would do for many wildlife shots, and try to crop the 5DIV even further to match it, there is no comparison. The 7DII has the advantage. The 1DXII, with it's 20mp sensor would be at even more of a disadvantage. That's lens for lens. Put a longer lens on the ff and the equation changes. It has nothing to do with a particular camera. It's about the difference between two different size sensors with similar pixel counts. For enlargements it works the other way and I would take the 1DXII every time.

Canon's current two best cameras for sports, action, and wildlife are the 1DXII and the 7DII. The 7DII has several advantages over the 1DXII and is the more logical choice, unless you are a pro. I've never used the 80D, and though it receives great reviews and has some nice features, such as the tilting touchscreen, I'll stick with my 7DII. It was designed for that type of work and yet it's landscape work is as good as any other Canon crop sensor. It's build and weather sealing are both superior to the 80D and it's frame rate can't be matched by any other Canon except the 1DXII. The 7DII's auto focus is excellent, and coupled with a lens such as the 100-400 L II it is almost instantaneous. A very hard combo to beat. Using an extender, either the 1.4x or 2x, with the 100-400 L II will limit you to f/8 and only the 5 center focal points. I've never found that to be a big issue. Don't know how that would be on the 80D, but I suspect it would be the same.
Personally, I would wait for the specs of the upcoming (so we are told) 7DIII to be released and see if that might not be worth waiting for. I understand that one of Nikon's crop sensors currently has an edge over the 7DII, so, I wouldn't be surprised if the 7DIII leapfrogs that. Seems to be the way it usually works between Canon and Nikon.

I purchased 2 of these to be able to use modifiers with speedlights on location. Creative Lighting may still sell these handy units, massive strong construction, and they allow the use of strip soft boxes, octagon soft boxes, and square soft boxes as well. I paid $125@ for them and they are worth every penny on location when I do not want to carry the studio to a setting or when battery power is all that I have.

As far as mixing lighting, I always shoot raw and shoot a gray card prior to each series. The Lightroom white balance adjuster will correct for color temperature, and from there I can adjust to my liking...no problem. Using the Pocket Wizzards, I often use my 22 year old Speedotron light bank with newer Profoto lights, Quantum speedlights and tungsten lights too if I need additional lighting in select spots. Manual is the only way to go using a good light meter. With universal triggers, there is no need to have the latest and greatest when your lights are operating in good condition.