I have owned magna porting and also the Pendleton Dekicker that was on earlier 460 Wbys. I would never again have a rifle with any type of integral brake.

If you want serious recoil reduction then magna porting is not the answer. For that you want a brake and of the KDF type.....they are the ones fitted to factory Wbys in the 378 based calibres. The Vais brake is a good compromise between blast and recoil reduction. On a calibre like 375 H&H I would use the Vais but would use the KDF style for bigger than 375. A mate of mine has a 338 RUM with the Vais and the recoil is similar to the 338/378 with the Wby KDF style brake.

Magna porting tends to disguise recoil for a couple of shots and as such can be good for field shooting. It also makes the rifle much more controllable. A 375 with magna porting will just sort of "sit there" like a 270 or 30/06, in other words you can shoot just as you would shoot a 30/06 from different improvised rests in the field.