Here is the list of guns I had a laser on, Glock-36 (guide rod laser) S&W 340 (laser grips) Colt New Agent (laser grips) Glock 19 (grip laser) Walther P-22 (rail laser) S&W 22A (top rail mount)
Here is the list of guns I have with lasers now.____________.
First the laser is another item that can fail. (batteries, laser, wiring, switch)
In an SD situation the time it takes to draw the gun and remember to activate the laser (depending on type) and acquire the dot (very difficult in daylight) is probably longer than you have.
Even the sights on the gun in an SD situation may be of little use, your heart is pounding, your adrenalin is pumping, hands are shaking, trying to process whats going on and what to do will not be easy. It could come down to point & shoot, something you should practice at close range.
Lasers are a lot of fun for target shooting and plinking, my thought is keep it simple for carry.
Also as mentioned with that beast on your pup I don't know what holster you can find.

Sorry for the rant.
John