OK thanks for the help!!
It seems like I've been misled by some claims made, particularly about Fenix lights. I thought that there was a way to get a single constant light output from a set of batteries and then when they ran out the light would simply go off.
But yes I see how this would be a problem in the more professional tasks SureFires are usually put to, because there is no warning before the cells run out and the light stops working.
I was just wondering because I can see myself changing the cells every time the light starts to dim, wanting the maximum output just because I know it's there. So I was hoping for something with a very consistent output.
I'm just trying to avoid the scenario of buying a light quoted at X lumens for Y hours and finding out it provides X lumens for 5 minutes and by the time it reaches Y hours you would be better off using a candle. This would cause me to only partially drain each set of batteries before wanting to put new ones in. Very annoying, wasteful and expensive! So I guess I'm asking which lights I should be looking at to get the most reliable consistent output that is actually close to the quoted lumens?