I'll be putting a lasermax on my Shield 40 any day now. Maybe tonight. Waiting for UPS just now. I'll let you know what I think. $77 from E-Bay.
The big difference I see is the Crimson trace turns on when you grip the gun and stays on as long as you grip it. With the Lasermax, there is a switch, you turn it on and off. I wanted the crimson trace, but, $100 more? I bought ammo instead. Practice will help me more than a laser will.