CAVEAT: I'm no trainer. So, this is JMO. Just some guy with an opinion.
There's been a lot of discussion about training in this thread, with most of it (seemingly, didn't actually count or anything) by those who are against WMLs.
Let's take your basic home-defender civilian. He's not ever going to be highly trained, no matter what he should do. He just won't.
If he believes someone is in the house who should not be there at night, what does he need to do? He needs to identify the source of his concern and determine if it is a threat.
From a safe gun handling perspective, what are the most important things he can learn with his minimal training?
IDK how they would rank, but in some order, these would have to be on the list:
1. Muzzle discipline - don't point at what you don't intend to shoot
2. Trigger discipline - keep your trigger finger outside the trigger guard until you have the target identified
3. Proper and firm grip of the handgun to control not only the first shot, but any others that may be necessary
4. Reacting the same way every time so you don't have to think too much
Which of those is most compromised by having a separate flashlight? #3 & #4.
Which of those is most compromised by having a WML? None. Remember, the spill light will identify any target with a down-ready position. So, if your "same way every time" is to be down ready before point, the the WML compromises nothing.
So, why is it, then, that the marginally trained gun owner is better served with a separate flashlight?
It is my opinion that most near-novice gun owners need to learn one way and one way only to handle, aim, and fire their weapon. Having to sometimes use a separate flashlight means they have to learn two ways. Maybe three, including one-hand shooting.
To me, then, the extra training mantra needs to go with the separate flashlight, not the WML.
It seems to me that it is easier to learn to visually take in the room with the gun down / light on than it is to learn 2 more ways to handle the gun and shoot.
Just another guy with an opinion...