I have a set on a .38 snubbie. Very useful in lowlight conditions as long as it's not raining/misty/foggy. They work then, too but the beam is visible and leads directly back to you. That may not be desirable. Then, again, it may not matter.
About legal lasers - showed up on another thread also. You can legally purchase handheld lasers up to 600mw. The CT laser is 5mw. I'd like to assume that CT knows what they are saying when they note that theirs is the most powerful that you can legally own but there are many sites that offer more power than 5mW.
See this link if you are curious. Handheld pointers in the 10mW and 15mW range are easy to come by and affordable. Be hard to mount on firearms, though. The CT at 5mW is plenty bright.