...
About a year ago, I got a rail mount Laser Max for my Px4 40cal.. which would be the same size and fit for a Px4 45.
Worked great, and very accurate, for awhile, then it it went from steady light to pulsing light. There are instructions how to sight it in, and to use either the pulse light or steady light.. Well, I had the adjustment just right, worked for some 3 months, then it went into pulse mode. So, I changed the batteries, didn't help, so I adjusted it far beyond what they say one should go to get it finally to go back to steady light.
That worked for about a month, then not only did it start pulsing again, only, but with every 3rd shot or so, the light would dim considerably, and the only way to get it back to full bright was to turn it off and back ON..
Time comsuming, put new batteries in hoping it was the problem (again), but no help, called them, nice people, sent it back, got a new one, and same deal, lasted about 3 months, then the dimming every 3rd shot or so.
Basically, I think it's a recoil effecting the ON - OFF switch problem, IMO, being up front, not to mention that the lens does get smoke on it, but that can be cleaned, and is no real issues with seeing the light downrange.
As far as going Red or Green, personally, since it is going to be used mainly at night, or in day time, it can be seen at 16ft, close range, but it's very clear to see, so I see no advantage of green over red, except to have something different, and pay more for it..
Good luck, but IF you can, hopefully you can find another Manufacture of rail mounted lasers that have better quality products built to last under recoil conditions.
You could also look into the front return spring cap area laser mounts, but I've heard some bad stories about their reliability, wire runs, external switch add-ons to frames, etc.. But the good news is that unlike the rail mounted lasers, you wouldn't have any problems using any of the holsters you now own, but with a rail mounted laser, you will find none of them will work, and there are very few choices of holsters out there that will fit the gun with rail mounted laser.
Ls