1. There is almost no difference in the size of the patterns regardless of choke size at home defense distances. Might it make a difference at longer distances? Sure. But I am studying loads for home defense, not deer hunting. And at these distances, there is no real difference.
2. Some folks said the Modified choke would have "better patterns". I did not find this to be true.
3. The main factor in group size seems to be the difference in the brands of ammunition. That means that if we want good patterns, there is no substitute for trying the different loads in your shotgun.
4. Different shotguns marked with the same choke will often have variances in actual choke diameter. Not a big deal, but chokes are not extremely standardized.
5. It's fun to shoot stuff.
(Thanks to Vern for the help)