"The diameter of our mount was designed for the image circle without IBIS. It means the amount of light at the corners is reduced when the sensor is shifted. We could correct it digitally, but we don’t want to do it: we don’t want to compromise our image quality. [...] Our highest priority is always image quality. We hope you agree!"
Given that the laws of physics have not changed ... do they plan to compromise image quality after all? I do not agree then.