I wouldn't think the bad guy would appreciate the laser very much. If it helps you shoot better, and it should, it is a good thing to add to the gun. A lot of folks have added them to their pistols because they help you shoot faster with more accuracy.
As far as the slug for home defense, I wouldn't choose it unless you live alone way out in the woods so an innocent bystander or loved one wouldn't have to worry about a miss or pass through.
