Spend your extra $150 Here:
It's your carry gun right? I was in a Defensive Shooting and the laser played a role in pushing back the bad guy...It Effed him up, got him off stride. I had to shoot him anyway (4:00 am) and used the laser to aim (while lying on the ground)
'Don't leave home with out one" You DON'T want to shoot the MOFO the laser can possibly convince the Drunk / Drugged AssWipe he might get shot.
I think S&W worked with holster makers / Crimson trace / others while developing the Shield so there would be an ample selection of accesories available upon the gun's release.
I carry a Kel-Tec PF-9 in the right rear pocket with ease and will ultimately replace it with the Shield. which is just a touch longer.
If it's your carry gun you'll want a laser and Tritium night sights