Well, I'm looking at a LumiLEDs presentation right now that is showing for February 2004:
55 lumens per emitter for the 1W
120 lumens per emitter for the 3W
215 lumens per emitter for the 5W
They missed four milestones alreadly along the way,
since 2002.
These are parts they "already had in the lab" and
these were the milestones for moving them to production.
Either they are waiting for challengers, before they
release these parts to full production, they are trying
to get the biggest bang for as long as they can out of
existing parts, they had production "issues", or they were
fibbing a bit.
Remember, these were supposedly parts they'd already built,
and had in the lab, and they have missed four milestones already.
The fifth milestone for May 2004:
60 lumens per emitter for the 1W
140 lumens per emitter for the 3W
245 lumens per emitter for the 5W
So, where are these, "we have them already parts?"
Also folks don't look at the datasheets too careful.
When they say an emitter puts out 25 lumens, you'll
note on the datasheet that it says Tj= 25 degrees C.
I have not seen a flashlight that is heatsinked/cooled
well enough to hold the junction temp at 25C.
If you look at the datasheet for the emitter, you will
see a Light Output Characteristics section. The one
I am looking at right now shows the light output dropping
by 30% when the junction reaches 120 degrees C.
Note they claim the die to slug thermal resistance of 15 degrees C per watt. So, if you had an infinte heatsink, which a flashlight is a *far* cry from that. Even if you could hold the flashlight at a room temperature of 25C, and you
had perfect thermal coupling from the flashlight body, to the thermal puck, and perfect coupling then to the Luxeon slug, and held the Luxeon slug at 25C, you'd still get a 5% drop in light output. Since we don't have all this perfect stuff, most luxeons probably have a much greater loss of light output due to heat. The ARC4 would be a perfect example of a LED in a setup that doesn't hold the LED slug at 25 degrees C.
Consequently, also look at the increase in light output if you cool the Luxeon below this. If you get that slug down to -50C, you get more than a 20% increase in light output.
Now, you toss in a 3W LED. Hold the slug at 25C, but we have 3W now (if you only hit it with like 700mA), but at 15 degree C rise in the LED die per watt. So, if we could do the impossible and hold the flashlight, heatsink puck, and the LED slug at 25 degrees C, the LED junction would rise by 15 * 3W = 45 degrees. 25 + 45 = 70C junction temp. Now we have a 15% loss in light output. But, because we don't have all this perfect stuff, you see a much greater drop than 15% drop in light output levels.
Then you take a look at the optics/lens/reflector/protective lens cover and you end up with a bunch of additional losses. Most extremely highly polished aluminums put on a reflector will only have 70-80% reflectivity. (this will degrade once develops it's characteristic aluminum oxide film due to our atomsphere) So, toss in another 20-30% loss. Of course, a person can go the spendy route, beyond flashing, and get a vacuum deposited telescope mirror type coating applied, with a protective coat, and dream of getting these losses down to only 2%.
Still we need the protective lens, a nice uncoated lens will give you about 8% loss, tack on another 6% per millimeter if you use standard float glass. Add on a real nice Broad Band Anti-Reflective coating, and you can get to 0.5% loss per surface (front and back), and then the loss of the glass itself.
And then you get to converters. Take a BadBoy boost converter, say you want to run that 3W at 1A, so you get a BB1000. Well, you stick two NiMH in the flashlight, and at 1A, the input voltage drops to 2.4V in a hurry, which causes further current requirements from the batteries, since it has to boost further. Before you know it, you are sitting at 60% electrical conversion efficiency. Thats a huge hit on runtime, and that 40% loss is going to turn itself into heat. Guess what? The luxeon then gets warmer, and the light output drops even further...
So, there are lots of areas a person can attack to improve the light output levels of flashlights.
Just my two cents...