I have had one fitted on my G27 for over a year now. It is an excellent sight except that mine now has a tendency to switch itself on when firing.
I have not bothered to contact Laserlyte about it as it is no big deal although I did find it annoying at first. I believe they have a fix for this problem.
It is well made, easy to adjust for windage and elevation, plenty bright enough in room light situations and at night. In broad daylight pretty pathetic as are all red lasers. The on/off switch is not as intuitive as a Crimson Trace. Does not interfere with any holster I have tried.
I agree with 'tampashooters' in that it is a bear to fit. Ideally use of a sight pusher would be good.
"The United Kingdom and the United States are two great nations but separated by a common language" - George Bernard Shaw
"A government which robs Peter to pay Paul can always depend on the support of Paul" - George B Shaw
Certified Glock Armorer