The mag capacity should not be a factor for PP, it should be familiarization and practice with your choice, comfort and carry. Reaction, muscle memory and well placed shots should get the job done quickly and with hopefully, no more than three shots fired.
Now if you plan on taking on many adversary's, I suggest an additional mag or two.
"There is no hunting like the hunting of man, and those who have hunted armed men long enough and liked it, never care for anything else thereafter." - Hemingway
“The greatest ignorance is to reject something you know nothing about.”