Laser dots are of questionable value.
First off, when your adreniline is up, how likely are you to be looking at your tummy, or checking a mirror for a dot on your forehead? The bad guy is most likely to be equally oblivious to his "targeting". Hopefully, he will have bought a buddy who will inform him "Dude, there's a red-dot on your forehead". Also, like using a flashlight, your nemisis can see where the red dot is origionating - IE, you've just given away your position.
That said, a laser dot can be handy to train a new shooter with, so you know where he/she is pointing, and they can index the idea of the muzzle's position being where the bullet will go. And with some shooters, it may give them added confidence in the HD use of their weapon. It also could concievably give you and edge in a dark shooting environment.
I'd say the jury is still out on laser dots, but my cat loves to chase it around.