Aarrgh, confirms my personal aversion to superfast lenses. They are big, heavy, extremely expensive , more or less soft, tend to vignetting and the additional stop you get for the price is for limited use only because of the extremely narrow DOF.
These lenses are specialists, stylish overkill for 95% of all opportunities in everyday life. And if a lens has such a serious and obtrousive distortion fault like this one, the remaining opportunities for its use are extremely limited. A lens can be a bit soft wide open, it can have a not too perfect bokeh, but such an amount of distortion is not acceptable.
Interesting to see tho, that the most superfast-fans are among those, who can argue in endless discussions, what the sharpest lens on earth is. Maybe it's more a matter of "nice-to-have" than "nice-to-use".
Peppo