It boggles my mind that anyone would argue in favor of a .22LR as an effective man stopper in a self-defense handgun. I could state that if this were the case, police the nation over would be carrying .22's instead of 9mm's, .40S&W's, .45ACP's, and .357 Sig's in auto pistols... not to mention those still using revolvers, and the military forces of the country. As has been pointed out frequently, the most important factor in using deadly force is stopping the assailant's attack as quickly as possible.
I am not going to debate this issue with anyone as I see it as a personal choice. One picks what one believes will work best for them. And that is how it should be. No one is going to know how their chosen caliber/load is going to work until they actually have to use it and even then, they are only going to know how well it worked for that specific incident. Knowing this, it just makes sense to me to have as many of the cards stacked in your corner as you can.
For those who believe a .22LR is their best choice, I say go for it. You will find out if you took the right decision if you ever have to call upon it to save your hide. Of course, this can be said for any handgun caliber, but prudence would dictate you listen to those who have been there and done that. I have and I am not of a mind to play games with my life or the lives of my loved ones.
So if it is a .22LR for you, good luck. But don't try to tell others that a .22LR is just as good, or better, than the proven and popular SD calibers. I wish you well in your decision and hope you come out on top should you need to use it. However, I would suggest you give serious thought to your decision before you make what could become a very deadly mistake. But then again.... it IS your decision to take.