IMHO, anything bigger than 44 magnum in a revolver is more of a conversation pice than a serious defensive handgun....
I suppose strictly for hunting with handguns, they have merit, but they are not the equal of a rifle...
If a bear is charging you, how fast can you and fire a 65 caliber Super Magnum Express handgun with an 18 barrel, that weighs 105 ounces empty, from a holster that's seven feet long?
A model 29, with a four inch barrel is something you can actually carry, draw and fire under stress, and it's about the limit for that purpose.