Talys said:
The one thing that I'm looking for that would make me buy this is visibly better higher ISO performance. If it can be as clean as a 6DII at least at ISO 800, I'll seriously consider it. If it's as clean at 1200-1600, I'll buy it in an instant. Maybe this will happen with a new sensor; don't know.
Unfortunately this is impossible. Even the best of the best APS-C sensors from Sony and Nikon cannot come close to a full frame sensor. Do not expect that much difference in APS-C sensor performance for at least another 10 years, maybe more... the difference is that big.
https://gyazo.com/f4b8b43e330014ad0088fda4982d499a
Here is a comparison between the 80D, Sony a6500 (best APS-C) and 6D mark II.
Here is another comparison... Canon 10D from 2003 vs Sony a6500
https://gyazo.com/cea02d897a0ccfd5da2b1c6387b88e7d
It took 13 years in sensor technology to make up that gap... and the gap between the 80D and 6D mark II is the same.
Looking at the graphs... unless you want to shoot the Sony a6500 at really really high ISOs like 12800 to 51200, you can't get close to the 6D mark II with an APS-C sensor... but at that point the quality is severely degraded anyway.
Unfortunately that is the decision we are left with... the only real upgrade path with a big difference in performance is full frame, and all the associated expenses with full frame glass.
Last but not least... a funny little comparison between the 1D mark II (from 2004) and the 80D & a6500.
https://gyazo.com/a557806e1be6739564cfc0491e368ec8
Purely from an image noise perspective... the 1D mark II (1.3x crop) from 2004 is damn close to the 80D.
Just goes to show how much of a big difference sensor size makes.
PS: The 80D obliterates the 1D mark II in many many other measurements like dynamic range, resolution etc, I'm not saying they are comparable in everything.