There is nothing new about using a handheld light with a handgun. The reality remains that, in the world of civilian self-defense, it is exceedingly rare (practically non-existent) to find incidents in which civilians engage a threat with gunfire while using a flashlight. This is because most crime happens in low light, but not no light, environments. Parking lots are fairly well lit in most places. Still, knowing how to shoot with a handheld light is a warranted skill.
It is a skill, however, that has been made more complicated than it needs to be. Years ago, I was taught, and in turn practiced with, different handheld light shooting techniques. I eventually settled on using a neck/cheek index hold for the light, and shooting single-handed with the light in that positions, which simultaneously lights up the target and the sights if held correctly. This hold, in my opinion, is the most practical and useful for concealed carriers. I long considered the well-established and often taught Harris technique only necessary if you must shoot from a strong-side barricade, as you must get the light on the other side of the gun in that circumstance. After attending a low light handgun course with Steve Fisher not long ago I changed my mind regarding the usefulness of Harris, as he taught some variations on it that make it quite practical.
Still, I am convinced that the civilian self-defender will get most use out of the neck/cheek index, as that is the position the light will likely be in under any circumstances as you must actually light up and identify a possible threat before you proceed to a shooting solution. Using an FBI type hold to search, then the neck/cheek index to shoot, and incorporating a Harris technique to shoot around a barricade is, most likely, all the concealed carrier would ever need to do in the unlikely event of shooting with a light in hand.
See an overview of these simple light techniques: