+1...Realized my post was stupidly long, so I'll sum up.
The only DocGKR post I saw specifically denouncing CD was made from a 1 7/8" .38 Special, where the bare gel had mediocre expansion and the denim failed to expand.
Apples, meet oranges.
I have yet to see the actual results of the tests on 9mm and 40, though I did see mention of the intent to test, but saw no results, except that as of February '13, Critical Duty 220 gr +P was added to the .45 ACP list. I understand that Doc does not update the list with EVERY type of ammo that doesn't make the list, and this is not irrevokable proof that ALL CD (whichever variety) ammo will reliably penetrate between 12-18" across all cartridges or across all platforms, but it does lend some credence to the bullet design.
While DocGKR's list is by far the most inclusive list of SD ammo, it is not the be-all end-all list. Not looking to stir the pot, I just haven't seen Doc's tests on CD in a 9mm or .40 S&W automatic, so I can't rightly say that it isn't effective. . .then again I can't rightly say that it is, either. Would I take it over FMJ? Yes. Am I waiting for some Fed HST to be delivered? HELL yes.
I am not a Hornady fan-boy and I have no brand loyalty when it comes to protecting myself and my family. Like the OP, I'm new to this and I got what was available and what I had seen some tests on. Frankly, I don't care if it's made in Slobovia and looks like crap, if it feeds and fires without blowing my face up and penetrates reliably, I'm good with it.
Besides, in the real world of "terminal effectiveness", the only ammo that effectively incapacitates an adversary is ammo that happens to strike the CNS. Even when punched straight through the heart, people have been known to keep shooting back for close to a minute.
I do know that I can fire every bit of 75 rounds of ammo on MY person, and grab another 20 off somebody else, and put THAT down range too in under a minute!
Ammo brand selection comes somewhere between low-consequence and irrelevant in the reality of a gun fight.
"I'm not worried about getting shot by HIM... he has Critical Defense brand ammo in his gun!" - Said by nobody ever
What DOES matter?
The ability to make a hit to the spine, or into the head, as quickly as possible. The only shot that stops a fight NOW is one that turns off the signal to the trigger finger of your opponent (brain hit). The next best option is taking out his ability to move (spine hit).
Regardless of ammo brand, design, or manufacture date...
If you can't shoot tight groups under pressure, with speed, while moving... it's all dumb luck.