Personally I feel that 9mm, 40, 45, 357 sig will all do the job if I need to use them in a defensive situation. The ballistics of all these have been beat to death and this has nothing to do with them.
Earlier I was at the range and several people had different guns (mostly Glocks) in 9mm, 40, 45, and 357 Sig. It was dark and we fired several different duty loads through each gun to compare the muzzle flash. With everything but the 45 the flash was almost non existent. In the 45 several different types of ammo, including gold dot, golden saber, and one other which I can't remember were fired. It looked like a freaking flame thrower. With the other calibers you could shoot and not lose night vision or brightly illuminate yourself as a target, but the 45 was orders of magnitude brighter that the others. You completely lost night vision after seeing the muzzle flash. Maybe there is some other type of ammo that is better, but from what I saw I would not want to be using a 45 if I was shooting in low light situations.
Earlier I was at the range and several people had different guns (mostly Glocks) in 9mm, 40, 45, and 357 Sig. It was dark and we fired several different duty loads through each gun to compare the muzzle flash. With everything but the 45 the flash was almost non existent. In the 45 several different types of ammo, including gold dot, golden saber, and one other which I can't remember were fired. It looked like a freaking flame thrower. With the other calibers you could shoot and not lose night vision or brightly illuminate yourself as a target, but the 45 was orders of magnitude brighter that the others. You completely lost night vision after seeing the muzzle flash. Maybe there is some other type of ammo that is better, but from what I saw I would not want to be using a 45 if I was shooting in low light situations.