The X-Factor of Fudging ISO

@Mr Moonlight... Thanks for the experimental data.  You can readily see that the Fuji ISO 6400 shutter is  10/1250 and the other ISO 3200 is 1/125, so the Fuji does inflate the ISO by 2x.  There is a variable in your test which I am not sure it affects the conclusion, but your focal lengths of 35mm and 85mm might confuse the issue for some of us.