Reduced recoil means reduced payload or velocity or both.
#4 Buck barely meets the criteria for a defensively load already. In fact technicaly based on the 12 inch ballistic gelatin penetration criteria only #1 and above is suitable (though I personaly think #4 still has its place). Reducing the velocity of any of these loads would drop thier ability to penetrate further, reducing payload would drop thier stopping power.
If you ever find yourself shooting defensively I think you will find you do not even notice the recoil or kick in fast paced or stressful situations, and a magnum load will not be a whole lot different than a light load. The same goes for hunting, one is hardly effected by the recoil of a magnum shell during intense moments. At the range you have time to think about it, expect it and be effected by it more.
For that reason one would likely do just as well with high power magnum loads for defense, nevermind normal and dimunitive( reduced recoil) power loads. Unlike a pistol the recoil is mainly taken by the shoulder and does not effect the speed of follow up shots at close range (at least I don't think so) even with excessive loads.
Trying to get 20 gauge performance out of a 12 gauge and calling it "reduced recoil" does not make much sense to me. Wouldn't one be better off getting the smaller and more convenient profile of a 20 gauge if that is the load they prefer?
