One of the members at Warriortalk asked about this so I thought a pictorial describing it would be a good thing.
Now, having shown all of this, I will add that I do not understand the lust for lumens. This is where personal real-life experience is so important...otherwise the focus is driven by dudes that may have creds, but are being directly paid by flashlight makers to promote the Lust For Lumens. (And please don't tell me such doesn't happen)
I was directly involved as a primary shooter - often the sole shooter - in seven gunfights between 1800 HRS and 0300 HRS. These were not theoretical shoot house events, or "surround and capture" events with fifty guys against one...they were killings, in reduced light, of killers that would have shot and killed me if I was careless with a light...regardless of lumens.
So I have opinions on the matter developed in the real world.
There is no need at all to speed draw a flashlight. If you cannot see because it is dark, you have the time to bring out the light proactively. Why do you do this? Wait for it...because it is dark and you don't want to fall off a cliff.
In urban settings, other than a proactive search of a dark structure, or a superficial search of vehicles, or when moving directly into a darker area, you will never need a light. Why not? Because in urban settings there is ample ambient light to determine the presence of a threat or pending threat.
I worked the bulk of my time between 1500 HRS and 0300 HRS.
If you are in reduced light and a fight comes to you, you will know it without needing to grab the light to respond. How do you know who the enemy is? This is tricky now, but listen carefully...the enemy you need to shoot is the guy that is shooting at you. His race, clothing, age, facial hair or sex are irrelevant information.
And most important - if you have an enemy that is a killer rather than some meth punk trying to hide in a closet of an abandoned house, the minute you start flashing and sweeping and strobing, the killer will fire toward you and the light. He doesn't care if it takes all his magazine to get you and never got the word about accountability of shots downrange. Trust me...the strobe or the lumens are not going to intimidate him or make him cower in fear.
All that said, it doesn't hurt to have a light and carry it daily. The Surefire Stiletto is, in my opinion, the best available today for everyday carry.