Jim has a point, and there will never be an "answer" as to which is better. But since I like them, I want to share why my decisions were reached, using some of the arguements against. Bear in mind, I'm only sharing, NOT condemning
"A flashlight on your gun makes you a target"
A FLASHLIGHT makes you a target, period. If you use any flashlight to randomly SEARCH your home, you WILL be seen before you see the perp. Don't use your light except to IDENTIFY the LOCATED target.
"I hold my gun away from my body to avoid being shot"
Any perp who's EVER been to jail knows to shoot to the low LEFT of the flashlight. It's kindof a coin-toss. The perp may shoot AT the light, he may shoot to the left of the light, depending on his/her experience level. If my flashlight is ON the gun and the perp is experienced, I'm the recipient of unaimed fire to my right. If not experienced, then I'm the recipient of unaimed fire directly at the light. 50/50 chance.
"You are pointing your gun at the target"
The best of all arguements. The only answer I have is to FOLLOW RULE #1!! Never point the gun/flashlight until you have FOUND the target, and believe it to be an intruder. OF COURSE, keep your finger OFF the trigger until the intruder is identified as a NON family member. That will prevent AD's and disaster.
If the threat is REAL, and I have a seperate flashlight, my gun is at low ready, and I'm one handed, with the light in the other. I have to bring to bear, aim (to some extent, depending on your personal method) and fire. Since BG's do NOT practice safe handgunning, their gun is close to the chest, pointed straight out from their body. They do NOT have to raise the weapon, and they will NOT aim AT ALL before they open fire. Sure, the chance of them hitting you is less, but the chance of hitting a family member in another room?
If I have a flashlight on my firearm, I have found the threat, cannot readily identify the person, so I point my firearm at the potential threat, finger OUTSIDE the trigger guard, and illuminate. If it turns out NOT to be a threat, then I go to low ready immediately, and find out why my brother-in-law is creeping through my house at 3:am!!!
If it is a BG, then all I have to do is move my finger to the trigger and fire! I've had several seconds to "AIM" and I am already in a good solid 2 handed firing stance.
Again, that's just my opinion, and I'm NOT saying I'm right and someone else is wrong. I'm just sharing MY logic on why I chose to have a flashlight mounted on my house-gun.
Whatever you decide... PRACTICE, and be safe!