A bullet wound is more severe when the bullet is supersonic, provided the shape of the bullet is such that it optimizes the shock wave that precedes and envelops it though the target. The supersonic shock-wave though is only useful for increasing the wound volume through soft tissue, a large bone will only reflect the frontal diameter of an expanding bullet, or the full caliber diameter of a non-expanding bullet. But whether 1800 fps has a significant advantage over 1200 fps I doubt provided through and through penetration occurs in both cases. I shoot cast bullets at both velocities from center fire rifles, and there is little terminal difference on live targets. I will concede that while the velocity of the faster bullet can make up for the mass of a heavier bullet, I have never seen evidence that it can exceed it. Well, that's not entirely true, as bullet impacts of 4000 fps result in incredible soft tissue carnage, so yes velocity makes a difference if you can get enough of it. There are two problems here. The first is that soft tissue damage cannot be relied on to stop a determined antagonist, and the second is that pistol cartridges can't produce enough velocity, and attempts to increase that velocity in any meaningful way reduces the controllability of the pistol, particularly when shooting from an unnatural position. Noise is another often over looked consideration. Your actions are reactive in nature, so you will have no opportunity to put on hearing protection. I can only imagine what it might sound like to fire a hot 10mm from inside the confines of a vehicle, an elevator, or a small rest room. While your gun might have more terminal performance, your ability to use that advantage will be degraded by the mind numbing muzzle blast of your first round, and if you have to shoot your man more than once or solve a multiple target problem, you might not prevail. A better solution is to choose heavy for caliber bullets to reduce the powder charge and thus the blast signature of the cartridge.
It is interesting that people who have a reasonable idea of the mechanics pertaining to the terminal effects of a rifle bullet on game suddenly get dumb about the effects of a pistol bullet on a 200 pound target. The only difference between Bambi and the Troll-That-Lives-Under-The-Bridge is that the goblin tends to be a vertical target while Bambi tends to be a horizontal target. The plumbing that supports life is essentially the same in either target, and if a bullet passes through either plumbing system, blood flow to the brain is impacted and the ability to sustain life is compromised. Once hit, if Bambi makes a hard run, that is no big deal to the hunter, who can easily track the spoor to his prize. Conversely, we do need to be concerned about what the goblin is capable of once we've hit him. The fact that we shot (at) the goblin in the first place emphasizes that our need to change his behavior was great, and if shooting has not diminished our peril, we will die. The idea that a goblin hit by pistol fire under realistic shoot or die conditions, will simply roll over and quit is beyond optimistic in a day and age when drugs can blank out pain or any thought of self preservation.
If we begin with the premise that a solid unprotected upper torso hit by a 12 ga slug will stop anyone and work backwards from there, we see that all service pistol bullets are lacking, however the frontal area of the bullet is the single most important ingredient to the size of the wound channel, as the velocity bracket of pistol rounds is quite narrow compared to rifle cartridges. There is nothing we can do to increase the velocity envelope of the bullet while keeping the gun manageable, there is little we can do to improve the expansion qualities of the bullet if we require it to punch through a windshield, dry wall, or a garbage can and still produce a behavior altering blow to our antagonist, particularly if your shot needs to break the pelvis. Again, the soft tissue damage possible from a pistol bullet is seldom sufficient to accomplish immediate incapacitation, which is the goal of the exercise, but regardless of that, you can only shoot at what you can see, and if your man makes it to cover,there might not be much to shoot at. If I were to carry on the street, I would choose a bullet similar to the one I carry in the bush. My bullet in the bush is a 325 gr hard cast WFN loaded to 1200 fps in a short .44 magnum, which produces a reasonable wound volume without giving up the controllability I need for a fast follow up shot. My other ATC gun is a M-27 .357 magnum with a 195 gr hardcast SWC at 1150, which again is controllable, penetrates very well, and isn't as hard on the ears as other .357 loads. On the street, my first choice is a full size 1911 .45 loaded with 230 gr truncated cone bullets. Yes I am long enough to conceal it in a proper rig. No, it isn't supersonic, but it is controllable, easier on the ears than some, it produces an acceptable wound channel, and it will break a large bone if that shot is presented.
In any street level human conflict, if there is a safe way to remove yourself from the situation, that will always be the first and best choice. But if violence comes to you and you are unable to avoid it, your best chance of survival is though training and the more realistic your training is, the better prepared you will be. Your brain is your greatest asset, not your pistol.