Re: question on tact lights and lumens.
Another thing to keep in mind with the lumens rating is it only tells you how much total light output there is. It does not take into account the beam shape/diameter.
So you can have one light with a huge beam dia. that will not be as "bright" in any one spot -vs- a very tight beam dia. that will be super bright and they can have the same lumen rating.
Since most companies do not give their beam degree it makes it hard to judge. The same was true of candlepower that maglite commonly quoted, it measures how bright a beam is, but not how much total light it puts out.
That said I think in most cases you are best served by using a tactical light to illuminate/stun someone and leaving it on until the confrontation is over from that point on. In most cases if you want something bright enough to really stun someone and blow their night vision, you also impact your own night vision. You usually can't flash the light on them then turn it off without significantly affecting your own night vision, depending on the distance they are at.