The father of friend of mine used to carry a stainless Vacquero in .44mag as his CCW. He carried spare loaded cylinders in his briefcase.
I can load mine one at a time quicker than I can get a cylinder out and another one in.
And there is the small matter of ammo falling out of the cylinder unless you keep it pointed down ALL the time.
There is one advantage to the Blackhawk....it points much better.
In a real case of self defense, it is going to be at very close quarters. At those distances, the guy who is going to go for two handed stance and using is sights will be shot before he even gets started.
In addition, most encounters will be in bad light where sights are worthless.
If we are most likely to need our weapon at night in our own home, imagine waking up a 3:00 AM to the sound of glass breaking. Your glasses are on the night stand. Your vision is blurred from sleep. There are no lights other than a night light in the hall.
Are you going to take the time to put your glasses on? It takes two hands, you know.
So you grab your gun, no glasses, vision blurred, sights worthless...I hope that gun points good and that you have practiced that very thing.
All guns have advantages and disadvantages. The advantage to the Blackhawk is that you can learn to be deadly under those conditions.
Of course some of the Smiths are really nice to shoot but for me none that I have shot are as instinctive to point as the Blackhawk.
And you can get a Blackhawk that is a cannon on legs...