I own a Model 29-2, that's been Magnaported. It's a four-inch barrel, and the Magnaporting has no effect on the recoil. I also have a Model 29-5, 5" barrel, that's Magnaported.
I came to the conclusion that Magnaporting is marginal, at best, in taming recoil or muzzle flip. My 7.5" Ruger Super Blackhawk does benefit. So the longer the barrel, the more benefit. I also did a side-by-side test using identical Model 19's, with 4" barrels. I concluded that there was no difference in the recoil or muzzle flip.
Magnaporting seems like it reached its peak of popularity in the mid-1980's. I owned a T/C Contender, 44 Magnum, with a 14" barrel. Even Magnaported, the gun was not fun to shoot after about 5 rounds.
My conclusion, and YMMV, is that Magnaporting just doesn't work well with barrels under 7.5"
The value of any revolver would be at least $100 less if Magnaported vs. non-Magnaported.