It's extremely important if it almost never happens.
There is data base on civilian shootings. The closest we can come to is LE gunfights. We must agree that the civilian and the LE profession will not necessarily be in the same situations - the Cop runs to the sound of gunfire. However, the civilian and the LE will likely be engaged with the same BG. So if we look at LE gunfights we see the following:
I am not a gambler, I survived over 30 years in some of the most dangerous areas of our country as a street cop. If want to limit your options and survivability by using 2 century old technology and no possibility of a combat reload, good luck. Maybe you will not need it, the odds are in your favor if you are willing to stake your life on someone else's opinion.