Bruce you’re missing the factor of the distance between the line of sight and the bore. Having been a master class sporting clays shooter in my younger days, I would be quite surprised if I could not get an accurate shot off with a shotgun more quickly than anyone with a scoped rifle. This is due to shotgun shooting technique, stock style and eye alignment to the bore. With a good set of irons, the best in my mind being equipped with a rear receiver ghost ring, you get the alignment needed for very fast accurate shooting at close range.
To give you an idea how accurate this shooting style is, Gough Thomas Garwood, one of the greatest shotgun writers of all time, mentions a unique H&H Royal that was built in .22 LR. The owner used it to shoot duck on the wing to a distance of 70 yards. Obviously gun fit was superb.
I go to extremes to get my scopes as low as possible. However, it is not possible to achieve the alignment you get with a good receiver ghost ring. Obviously, drop at comb has to be set for this, but if it is, you can get close to the speed of a shotgun.
Interesting thought, why are big doubles not equipped with ghost rings as opposed to express leaf rear sights?