But the difference between a 26 inch rim and 650b is 12mm radius which is the only important figure. Diameter makes the difference look bigger but radius is the important thing.
It isn’t the only important figure but the last time I tried to point that out you didn’t understand either! And the change in radius is just as proportionally large as the change in diameter.
Lots of riders can’t detect significant differences in tyre pressure. That doesn’t mean it doesn’t matter! Everyone is agreed that there is a big difference in bike handling going from 26 to 29 so it stands to reason that there is a clearly perceptible difference between 26 and 27.5, especially as the trend for 27.5 tyres is towards higher volume that we saw with early 29 tyres.
Flip flop, as I call it, is related to the vertical movement of the head tube as you rotate the steering of a bike, it’s part of the self-centring mechanism of a bicycle.