I don't know if multiple .22 hits are better one 9mm hit, or any combination of comparisons as such.
But I DO know, that a .22 is better than absolutely no firearm, which is what I would carry if the Taurus did not fill that role.
I've never made the argument that the .22 is superior to anything else, except for bare hands. If it doesn't fire, its no worse than starting with bare hands. If it jams, its no worse than bare hands. If the rounds fail to stop the assailant, again, no worse than bare hands. I went the first 21 years of my life without carrying guns, and sometimes still do. (and live to tell.) So if I'm already wearing something condusive to throwing a .22 in, why not?
PLATED,
If you decide that you are not going to carry it, do consider a Ruger MK or Browning Buckmark for target shooting, as they are very accurate, with good triggers, and great reliability reputations. The Walther isn't bad but it does get alot of negative reviews, and lemons get out regularly.