I need some more soak time to see... I've owned several of the top cameras... G3, G4, S7E, 6P and now a G6.. I'll have plenty to compare. Sensor wise, the G6 is pretty much analogous to the G4/5 sensor... Similar pixel size, etc. They just went to a 4:3 format. Optically speaking, 4:3 is better than the wider 16:9 format as it puts more pixel sites closer to the center of the lens.
So between updates to the sensor, the better image handing of the 821 vs the 820, the 6 should out perform.
Now, the G4 was feast or famine... It took good pics, but it also sometimes went out to lunch and focused like a stoned college student at times. And in lower light, the color accuracy went into the toilet. Processing wise, I'll need to examine some more pics to compare the two. And I'll have my 6P as a baseline... That takes the best pics of the any of the phones mentioned.
It's kind of foolish to make a judgement without looking at a bunch of pictures... There's a lot of variability that just isn't accounted for if you look at a limited set. But I'm an obsessive ***** when it comes to stuff like this, so I'll get what I need to come to a conclusion.