Night sights are nice, but...they do not illuminate your target. If you plan on using stealth to engage a target in poorl lighting, be prepared to answer some pretty serious questions about why you shot the target. Weapon mounted lights will enable you to IDENTIFY the target, but they will give away your position. Lasers are worse than useless IMHO.
Personally, I like to have night sights and a good flashlight at all times.