I bought a separate green laser, rather than an integrated Crimson Trace for various reasons.

I have the option to pressure switch activation (which won't stay on, I have to hold it to keep it on), or, I can have a standard button that clicks on and off (and stays on / off).

I'm thinking that in a home defense situation where I need to pull the Rifle in the ready, I will not want to be fumbling with turning it on and off with a pressure switch, like I may do with the flashlight on the gun.

So, I'm thinking leaving the standard button on the laser is optimal. I'll turn it on when I pull the gun out and leave the pressure switch for the flashlight.

What are your thoughts for a situation like this?

I'm of the opposite opinion. Fumbling with an on/off switch as opposed to a pressure sensitive switch doesn't make sense. With the pressure switch mounted either on the pistol grip or forearm and the master switch on, seems a no brainer. Either way, you need to train yourself to do either one to get the muscle memory to accomplish the task while under stress.

A nice high powered green laser giving direction of fire to your enemy as you come around a corner or slice the pie sounds like a tactical disaster.  I have a cheap green laser and the thing will light up a room to anyone with dark-adjusted vision.

Agree with the above poster.  Also, I'm not a big fan of lasers as aiming devices, they have very specific quirks you need to be aware of before trying to use one.

I would either leave it off altogether or at least use a pressure switch. The last thing you want is to wave around a laser beam.

Personally I'm not a fan of lasers on home defense guns. Maybe I just need more experience with them. None of the training I've had involved lasers. Red dot and a light for me, but to each their own. Just be sure to train with whatever you use.

I am curious about the use of properly zeroed lasers, particularly on pistols.  On a carry pistol, for example, your irons could be zeroed @ 15 yards - the laser @ 50, or even 75m.

You could do that, but good luck explaining why you felt someone 75 yards away was a deadly threat.

God forbid I ever shoot anyone in South Carolina.  In Texas, deadly force can be applied in more circumstances than in South Carolina.

They are good for specific things.  It's just a tool.  If you understand the tool, you can use it effectively, if you don't understand it, it's a mess. 

In situations where you have to shoot a pistol one handed, in an awkward position, or holding something with the offhand, a laser is a fantastic tool.  Likewise, when searching in low light, using either a WML or a handheld, I have found that my speed is quicker with the laser vs iron sights.  The process of Light-Identify-Pick up sights-Aim-Fire is sped up because my eyes don't focus back to the sights.  My eyes stay focused on what I am identifying with the light.  That's just me.  

It's also a great tool for moving targets.  

Most people have a hard time keeping the dot steady, because their technique is poor, they don't index properly and aren't used to seeing how much their sights move when shooting.  The result ends up being a tendency to yank the trigger while trying to keep the dot on target.  You have to train to shoot with the laser, just like with regular sights.  I've found that dry fire with the laser has done a significant amount to improve my pistol shooting.  Go to any public range, and you will see that occur.  

I keep a Crimson Trace unit on my HD pistol (M&P9fs), as well as a WML with a handheld as well.  I can search with the handheld (preference) or the WML, while my trigger finger is indexed on the frame, which blocks the laser.  I'm tempted to try a vis laser on my HD carbine, but I haven't found what I really want, as of yet.  

Rather than using a laser, I prefer point shooting. If you train your fundamentals into muscle memory, you don't need a laser--at least for HD purposes (unless it's IR and you have a NOD, then they come in handy). For CQB, you learn where your muzzle is pointing if you train enough.

I'd go pressure switch activated.  There is no part of an illum device that should always be on.  But a more practical matter think about how dark your house is at night.  I doubt it's pitch black and you could probably see pretty damn well with no illum.  I think a flashlight for PID is much more important and it allows you to shoot how you normally shoot, not have a shooting method for dark and one for everything else.  Just my two cents.