I don't have a red laser light, but have shot guns with them on. What I have seen with the red light is that if you want to shoot it in any thing that resembles bright light, its hard to pick up the dot. Also any distance is a factor. I had been looking at the Viridian lights, and picked one up at an NRA show for less money at the Viridian booth. It does not have the bright white light along with the green laser. Its just the laser light. I mounted it on an XD .45, and no question about it you can see and pick up the green light easier in light and at a greater distance.
On sand bags, I was not aware how accurate my XD could be, shooting it using the laser sight. I guess maybe 54 year old eyes may come into play using iron sights. Standing two handed hold was the same results. Once you have the dot zeroed to point of impact you can be more accurate than using iron sights. For me anyway.
I'm glad I spent the extra money for the green laser, because I don't think I would have been happy with a red light, just from what I have seen of red lights. I believe the Viridian is a quality light. I think they were one of the first companies to develop the green laser sight.
Now for personal defense I'm not sold on a laser light. I have used iron sights all my life, and in a pressure situation I think I would automatically look for sights. In a dark environment the laser sight would be better, just because you can't see iron sights in the dark. Also a laser sight adds size and bulk to a carry gun, unless you get a grip mounted laser sight. I do keep the sight mounted on the XD for home defense, but I feel the shotgun beside it would be my first choice. The green laser sight certainly is fun to shoot with. From my personal experience the green laser is certainly worth the extra money.
http://www.viridiangreenlaser.com/
