Good article and interesting read:
My wife is not much of a shooter and she is recoil shy, but can put all 9 rounds on a pie plate at 20 feet with her taurus model 94 .22 lr revolver. She likes it and is confident with it. As I have said before, in a SD situation, you have to be comfortable and proficent with your weapon. If the 22 works for her, then there you go.