I've just upgraded to the 5DIV from the 5DIII. Currently I'm finding that with the exception of battery life and the number of images that will fit on my cards, everything is better compared to the mark III, but no one thing is hugely better. I shoot landscapes mainly for pleasure but sell a few images every now and then, take fitness portraits in gyms for a bit of extra income, do some paid product photography, and shoot sport when the fancy takes me, so basically everything except the product photography will get some benefit:
- the process of getting ready to shoot a landscape is faster (in-VF level indicator, low light AF) and the files thus far appear more detailed and malleable, but the DR jump won't be enough to stop me bracketing except in rare cases.
- for gym shoots I can now mix ambient with flash and not have to take extra shots to avoid green/purple cast, dim frames etc. Also, my favorite third party lens (Tamron 45) focuses much better on the new body with the outer AF points.
- for sport I'm sure that the better AF, better control customisation, cleaner high ISO and cleaner shadows will all prove useful (given that I'll mostly have no control over light). I suspect I won't even notice the bump in fps but we'll see.
For me, the cumulative effect of all those tweaks made the upgrade worth it, but not at full price (I went the grey import route and saved just shy of £1000 GBP). Even so I couldn't really justify it in any kind of financial way
Whether it would be worth it for you (OP) I can't say. Given that you've got a 7D2, do you think you might want to rejig your lens collection if you get a FF body? And what about lighting (strobes, triggers, modifiers, stands)? Tripod? Saving cash on the body could leave room for such things, and they could make a much bigger difference to your photography. If the 7DII keeps you happy for sports / wildlife etc, maybe a used 6D would be an even cheaper option for landscape and portraits? That said, I've always found that splashing out on a new body inspires me to put more effort into my photography