Are you really asking whether a pistol slide mounted red dot sight (RDS), such as on a CORE, works for various kinds of self defense?

There are two questions here and the answer is yes to both. The gun works. The sighting system works particularly well for pistol self defense.

For concealed carry, I think the 5" CORE version would be too long for AIWB which I prefer. The shorter 4.25" CORE works fine with a red dot.

For OWB or kept in a quick access safe for just home defense, I would use the 5" version.

RDS are starting to gain popularity on self defense pistols. They increase accuracy and speed when you need to use sights. At close range for point shooting they provide an even better index on the top of the gun for alignment without looking through the window. This is not a handicap.

The red dot floating in the window allows you a much greater (still small, though) margin of error for sighting onto a target in a stressed situation. If you can see the dot and it is on the target, the bullet will go there.

For instance, if the dot is in the lower right quadrant of the window, but on the target, your iron sights (which you are NOT using) would be out of alignment. Your front sight would be almost invisible behind the right side of your rear sight. If you were trying "to focus on the front sight", it wouldn't be there, but you don't know whether it is out alignment by a lot or a little.

But it doesn't matter if you see the dot. Your sight alignment does not have to be so precise. The dot/window combination gives you more alignment latitude.

Only when the dot is right on top of your properly aligned iron sights and on target will the two different sighting systems be co-witnessed. So, if you point your pistol naturally so your iron sights are aligned and on target, as you should with a lot of practice, the dot is going to be there. The advantage comes when your irons are slightly misaligned but the dot is visible, you shoot with confidence--while ignoring the irons.

Now, for all those who claim to be able to predict when and how you may be called upon to use your self defense pistol: BS. You can't prepare for the lowest common denominator and then expect to win a fight when the conditions are different. You cannot predict what kind of deadly encounter you will encounter. Prepare for the worst with the best training and equipment and you can handle the simpler stuff. Not all pistol use today is the classic 0-10' close encounter of the worst kind with one adversary.

Active shooter? Multiple assailants? Increased accuracy for a head shot? Long range justified shot? Sure, you won't take the shot if you don't have the equipment (your BUG .380 that is so easy to carry) or training and confidence to do so, and you get to relive people getting killed because of your decisions.

A 5" (or 4.25" if carried concealed) CORE with a Trijicon RMR and good co-witnessing suppressor height iron sights, and an enhanced trigger as your equipment will hit head shots at 30 yards and CoM at close to 100 if you can do your part. This would be a measured, calculated shot that can still be absolutely legally justified.

If all you have is hammer, then every problem needs to be a nail. If your self defense pistol has more capability, you have more capability. Accurized pistols with modern sighting systems are a change, an upgrade, and people resist change. Just as an RDS on a .556 carbine has proven to be advantageous, the pistol RDS will become very commonplace for extending the pistol's capabilities.