Ever wonder why green lasers aren't out in general production? Because the green LED technology isn't up to the job. In fact, firearm-grade green laser diodes are nonexistent, & appear to be a long way off, if even on the horizon. Surefire had plans to release one, but never did make it happen. Currently, the only way to produce a green laser is by splitting the wavelength of an IR beam w/ a crystal. This entails 2 problems:
1) Use of relatively delicate assemblies that aren't up to the abuses of firearm recoil.
2) Since the IR beam is being split, the amount of energy needed to get the green beam is actually twice what would be needed if a green diode were possible. Thus, more energy (200%) is being consumed, & more heat is produced in the process.
In truth, the light color alone isn't the only factor to consider. Background colors can obscure or enhance visibility for a particular beam color. Don't skip over red lasers. In fact, I didn't. I got a great (screamin', actually) deal on a Laser Devices OTAL via a group buy psonsored by Ci4Grant on the equipment exchange (way back when). The OTAL is compact, & I guarantee you can't miss its sigature.
Bottom line: Go w/ a quality red laser & have no remorse. I recommend a LD OTAL for the primary, & a LD BLAST for the backup.