The Crimson Trace LG-489g is an effective unit, with one possible exception. It's grip actuated, hence easy to use, but the switch takes up space near the trigger guard that might be better utilized with an higher grip (better recoil control). Green, red, doesn't make much difference in practice. Both have the same intensity, except green is somewhat more visible. Red won't affect your night vision. I've used both, but will probably stick with red in the future.
Make sure you practice as much or more with the iron sights. Batteries fail and the screws loosen under recoil. In a crisis, the laser might make all the difference you need to stay alive.