Say For about 9 years when I was shooting skeet/trap in the Air Force--Browning was my sponcered gun, I shot a 32" bottom ported o/u with high post rib.
Loved the gun and it performed very well for me. The porting seemed to keep muzzle jump down when I would shoot doubles, but honestly I don't think it's worth all the talk. Just something that may help a shooter subconsciously score better.