A defensive pistol is one you have decided to bet your life on. If you choose a mass-produced pistol, are you willing to settle for one that was built, as they used to say, on a Monday?

I'm not. I consider anything I can do to the pistol that helps me survive the worst minute or two of my life as well worth doing. I have a trusted 'smith look at the gun with an eye toward reliability and accuracy with my chosen factory ammunition and I'm open to switching ammo if it can be shown that my current choice isn't optimal. I want any questionable gun parts replaced or their interaction with other parts smoothed as necessary. I will already have looked the gun over to the best of my ability and test fired it in depth but I'm getting old and want an expert to double check me. 

I require the type of iron sights I can see best under all light conditions augmented with Crimson Trace lasergrips for low light conditions. I prefer a red laser because green tends to be bright enough to interfere with my night vision. Crimson Trace offers a wide variety of grip designs but I use the plain black rubber ones because they give me the best grip on the gun. I don't like gun-mounted lights and carry a flashlight instead. So-called night sights don't work with my eyes, they look like fuzzy balloons and when it is dark enough to see them I need a flashlight to identify a target anyway so I've learned to shoot with a hand-held flashlight.

I have no aversion to using a red dot sight on a defensive pistol or using a laser as long as you practice enough with them to "find the dot" quickly and realize the distance limitations of using a laser in bright daylight. And, I don't believe in trusting my life entirely to things that run on batteries so I always want the iron-sight option of three white dots on black sights.

So, I guess the short answer is I don't see anything wrong with modifications that make a gun faster for you to shoot more accurately and reliably under a wider variety of conditions.