Lasers are like any other tool, they have advantages and disadvantages.
On the plus side, they let you focus on the target, and they allow you to fire accurately in situations where the sights are useless, like as you are being knocked on your ass by an attacker.
m58 covered the minus's pretty well, moving parts and batteries add more things prone to failure.
If you are to tense to use the sights will you be able to switch the laser on ?
If the switch is big enough to manipulate under stress will it snag on the draw ?
And lastly, don't allow yourself to replace training with technology, that's what many cops do and they generally shoot like crap.