I have both crimson trace lasers and a green viridian. The green laser is way more visible in bright light conditions but it also requires a unnatural reach forward or the trigger to enable it. The green laser takes 5 or 6 times the energy or a red laser so it will burn up batteries faster but outside of long practice sessions its not really a concern.
The viridian is so bright at night its almost distracting. The other problem I have with the viridian is trying to find a holster that will accept it. There are one maybe two plastic holsters that will accept it but I have yet to find any leather holster that will accept it.
The crimson trace IMHO is a lot more natural to use in a self defense situation even though its not is bright in bright daylight.
As for the detractors of lasers, it a lot like the people who claim records or 8 track tapes sound better than cd's or dvd's... Oh so much non scientific nonsense.
If your laser is aligned correctly and your concentrating on your laser and not your front sight in a SD situation then you know right where that bulllet is going when it leaves the tip of your barrel and follow up shots the same way.
Yes you can do the same type of thing without a laser but unless your aiming at a particular button or other easily identifiable item on a BG your consistency of shot location will likely suffer.
The typical detractors or lasers have never shot with one or never shot enough to get comfortable with using the red or green dot as a guide instead of the front sight.
What you often end up with in this situation is someone trying to use the front sight and the laser at the same time and hesitating because looking at both takes a millisecond longer.
In the end its a personal choice, but I have yet to find a single person who I have allowed to shoot with my laser who doesnt like it better than shooting without it once I show them the right way to shoot with it.
Now Im waiting for the 8 track come back