I would suggest against it honestly. The only real tactical advantage of a laser is going to be negated by the fact that it is also telling the bad guys not only where you are, but at what angle you are shooting from.
Lasers point two ways = bad for you.
I would recommend a super bright flash light instead if you HAD to place something in the picatinny rail of your new pistol.
However, if you are in the market. Crimson Trace makes a pretty good product and their customer service, from the limited amount I have dealt with them, was good.
Beamshot is kind of bulky and the only one I have used seemed to have a splash pattern at the end of the beam. It wasn't real clean and crisp. Could have just been the model I was using though...
About the best laser I have ever seen was made by Surefire and it was retrofitted into one of their light housings to go on picatinny rail for an AR. That damn thing was awesome, and you could see it even in regular daylight. I think it goes for like $600 or $700 though.
Personally I would not only NOT get a laser for a home Defense gun I would strongly recommend against it .
The reason is simply this , if you live with others and have a tendency to check out every little bump in the night you will end up at some point , pointing your gun at a friendly which alone is bad enough .
Going on this premise I would rather have a light for 100% identification of my target and then there is a second reason that is every bit as important as the first and perhaps more .
A laser isn't just light that you're shining in someones eyes it can and does do real damage to the eye .
I recently read an article in my local paper that the FBI had been called in to investigate incidents of people aiming laser pointers at commercial planes as they landed and some pilots have suffered permanent damage to their eyes from it .
Lasers of high quality and durability like a Crimson Trace ain't cheap and run nearly $300 even then when the bullets start flying you wont be looking for that little dot you'll be focused on your opponent shooting at you and wont even notice that dot .
Go with a ultra bright light "80+ Lumen's" like JD suggests and the center of the beam will serve you just fine as an aiming point in the real world and it will ruin an enemy's night vision giving you an advantage while helping you ID a target to be 100% certain that it is an enemy that needs to be fired on .
In the end a light and perhaps a Tritium insert on the front sight would be the best setup you can get for a night fight .
Crimson Trace has a DVD that they may send you for free . Some very knowlegable people contradict the advice of the nay-sayers above . Some police departments like lasers . The laser can intimidate your opponent . It can allow an aimed shot even if the pistol is not at eye level . It goes where your eyes naturally look : at the threat .
If the laser fails or can't be seen in daylight, you revert to your iron sights ( or in the case of Glock, PLASTIC sights ) . I read that a company is making a bright green laser that works in daylight but eats more batteries .
You should not use a gun-mounted flashlight to search unless you are sure there are
no friendlies around . Use a separate tactical light to avoid pointing a gun all over the place .
Check the Crimson Trace Web Site for a video clip .
I do not like tritium inserts. They are costly and hard to pick up even in pitch dark .
I think the pros and cons are all covered, but I would take issue with not pointing your gun where your flashlight is shining. You SHOULD be pointing your gun where your flashlight is shining. If you're searching for someone you may potentially engage with a firearm, your muzzle SHOULD go EVERYWHERE your eyes go. You don't look first then cover the area with your weapon. If you do need to engage, it's too little too late at that point. No matter how good someone thinks they are or might actually be, action beats reaction every time.
Trigger finger discipline is key here. You cannot ensure that a person is a "friendly' until you identify them. If they are not a "friendly and they are not covered with your weapon, again too little too late.