A few yrs. ago I had 2 in 7 1/2", one 2 ported and one not ported, I had numerous shooters at the range shoot them both and NO ONE could tell the difference. On the other hand I won a free Magnaport job and had a 14" contender in .35 Rem magnaported, they put 4 ports
It turned it into different gun. worked great. A friend had 2 6" m29s, one 2 ported and one no port, no difference, some shooters even felt the no port recoiled less. I won a M66 S&W with 2 1/2" magnaported barrel, no reduction in recoil, super noisy, never shoot one from the hip, blow your head off, now has a 4" non ported barrel. My thinking is you need a long barrel for the leverage and probably the 4 ports help and a cartridge that generates a lot of gas is also a key factor. In a 7 1/2"
.454 you might get a litte reduction in lift but your gonna be deaf if you shoot it much hunting without plugs.
H08