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.