Some years back one of our officers tried one of the early type laser units on his Glock 19. At the time we did a fair amount of night fire. He brought his toy out to the range while everyone else either used a light, Harries style, or went with the white dots and muzzle flash. He was by far the slowest, chasing his dot.
About five years ago I won a CT unit. My wife had a M37 Smith and she wanted to put it on her gun, so we opted for that one. After a few years she took it off and we sold it on the web. The objections we had to it were that with any kind of decent firing grip the laser was going to go on, whether you wanted it on or not; due to grip design the gun's recoil hurt like hell even compared to the stock grips (since changed, I hear); and the whole lashup just slowed matters up compared to doing serious night fire. With a decent flashlight I have light or not as I wish; it is fairly blinding; and If I light up something that needs shooting, I am going to be shooting NOW. All I need is a flash sight picture at social distances.
As for training, there's always dry fire or, with a wheelgun, ball & dummy. Sight alignment and trigger control are mental processes, not something that comes in a box.
Sorry if this busts anybody's bubble, but I don't think they belong in the 3 feet, 3 shots, 3 seconds world. The money's better spent on practice ammo, IMHO.