Worked well enough at the O.K.Corral. Should work effectively on today’s accostive street vermin.
Do your part right, it will work fine.
Though the OK Corral is a poor choice for an example. The bad guys hit with .45 Colt shots all shot back, once, at least. The only one of them who didn't was the guy Doc put down with a 12ga.
And, as to standards, they are fine things, when they cover the most likely situations and then some. But, unless your standard is complete penetration from every possible angle, then the real world will eventually put someone in a situation where meeting the standard is not enough.
Would I be ok with something that didn't meet the standard for SD? No. Am I comfortable with rounds that do, and go no further? Yes but not as comfortable as I am with something that goes beyond, and then some...