I am firmly in #2 group. I can't imagine walking around hunting with tape over my master eye. Maybe it works for shooting at a range, but not hunting.
Years ago--back when rifles were OK on college campuses, there was a really well designed research study at Penn State. They took a large number of beginning marksmanship students and divided them up so that some learned to shoot rifles based on "handedness" and others based on master eye. The results were statistically significant that the master eye students shot higher scores. This was with .22lr position shooting. I think the effect with shotgun would be even higher.
