I got a chance to take a training course with a low light component recently. Here are some thoughts.
If you are using a hand held flashlight, it's really really useful to have a lanyard on it that you can wrap around your wrist, for when you need to reload or clear a malfunction, you can just let the flashlight hang (after turning it off ideally).
I'm not a fan of flashlights where you push the tailcap switch gently for momentary use and click it hard to keep it on. Under stress, you'll pretty much always click it hard, which is undesirable because now you have to click it again to turn it off. This is assuming that your style is to turn the light off most of the time, which may be too complicated for some (possibly including me).
The ideal flashlight switch style would have different motions for momentary and permanent on.
The Crimson Trace Lasergrip on my Dan Wesson PM7 1911 fared pretty well. It held zero over about 500 rounds, and was very useful in fast shooting, especially on multiple targets. In near full darkness it actually also helped light up the target a little, enough to see features on the target. One downside to it, is that it's another switch to manipulate, especially if you want to have discipline about turning it off as soon as the shooting is done. To illustrate:
A target appears. You:
- light it up with the flashlight
- decide to shoot
- activate the laser
- switch off the safety
- pull the trigger several times
When the threat stops (but theoretically there may be other threats there so it might behoove you to turn the light off):
- click the safety on
- deactivate the laser
- deactivate the flashlight
That's a pretty complicated dance to do, and would be simplified with no laser and no safety lever. As always, it's a matter of training and doctrine. e.g., one could train to do this dance proficiently, or one could choose to just not turn the light/laser off or re-engage the safety at this point. When shooting normally I have no problem clicking the safety off and on without even thinking about it, but throwing in the light and laser was causing me to get my wires crossed a little.
The Dan Wesson PM7 did not fare so well. It was having some major malfunctions where there was a horizontal stovepipe and the slide would not move forward or back without a lot of fiddling with it. It's going to be on its way back to Dan Wesson pretty soon. Unlike most other companies, which email you a shipping label, Dan Wesson sends it to you physically, which is kind of weird. I'm hoping they can get to the bottom of it. It's apparently pretty unusual and only reproduced about once every hundred rounds.