Nice, the 6750 model from a third party lol I know you're not a huge fan of the A7ii, and I don't dabble in full frame, but would another of the A7 cameras fit your needs?
I'm pretty invested in Nikon now, so I'm not seriously switching unless something really blew my D750 out of the water -- Or if there are eventually good AF adapters for Nikon lenses.
If there were good AF adapters -- (Commlite is about to launch the first Nikon AF adapter but early reviews are horrible.... so if they work out the kinks...)..... Here is what I would be looking for in an A7 camera:
-- The A7rii looks fantastic, but I am never spending $3000 on a camera body, and I have no interest in 42mp. 24mp is perfect for me. I don't want larger files and a slower camera, dealing with megapixels that don't really give me any benefit. And that are increasing the price of the camera.
-- Especially if they don't make a good Nikon AF adapter, I couldn't seriously go to FE without a much bigger lens selection, and preferably a little more affordable.
-- While the A6000 is mostly fast and snappy, everything I've seen with the A7 series is rather slow. Needs faster FPS, needs a deeper buffer, and a faster processor.
-- The Sony flash system is still a major drawback.
-- While I want 24mp, the A7ii is using a very old sensor. It's performance is far worse than the D750. So give me a new 24mp sensor.
Essentially, I can't see Sony convincing me to change for my main camera, any time soon. While there are things I like about Sony, for my core needs, Nikon is a better fit. (great lenses, great image quality, fast responsive camera, great autofocus). The bigger possibility is that a Sony APS-C mirrorless starts getting a lot of attention from me. For now, I'm on the fence about how often I'll really use the A6000. If the A6100/7000 blows me away, I could turn around and re-sell the A6000 and upgrade. (I basically only paid about $300 for it, so even if I only go $250 for it re-selling it, it wouldn't be much of a loss). I do want to try a few more side by side ultrawide zoom shots. So far, this is where I'm really on the fence. The A6000 shots feel very inferior to me for a few reasons, but maybe its in my imagination. The shots with the A6000/10-18 feel much softer than the Nikon with 18-35. It feels like there is much less dynamic range. And I got some weird sun flare the other day with the 10-18.
I was hoping that the A6000 with 10-18 (which is a well reviewed lens) would be good enough for me to become a walk-around vacation landscape camera. So I want to do a bit more side-by-side to see if the differences are real, or in my imagination. Ideally, if I end up being happy with the 10-18, I can imagine going to Disney world with both cameras. Some days just carrying the A6000. Some days, carrying both -- Keeping the D750 with prime lens as my dark ride camera for maximum ISO performance. The A6000 with 10-18 for landscapes. Then maybe just 1 or 2 more lenses for some general purpose stuff. 2 camera bodies with no more than 3 lenses in a day, should be a lot less lens changing than 1 body with 3 lenses. (If I had just the D750, I'd definitely go with a fast prime for dark rides, an ultrawide lens, and then probably my 24-70/2.8 as well for general purpose. Then I'd have a telephoto mostly at the hotel, but coming out for Animal Kingdom. )