I've thought about this, and maybe you are right, But this would mean a great leap in efficiency from the Xenon bulb. My experience is the following.
I have a 12V LA assembly from emillionworkshop in a 3 cell Ultrafire body, driven by 3 Batteryspace 650 mAh RCR123's. Runtime is about 20 minutes. Claimed Lumens are 200.
From my simple arithmatic, this setup produces almost 2 Amps (3 x 650), which at 12 Volts (RCR123's hold their voltage pretty well under load, I have learned?) would mean around 24 Watts. These are all quite high numbers, and comparable to P91 output? So I am tempted to believe the 200 Lumen claim, maybe even more.
This is backed up by my field experience when comparing this setup with my TL3 bulb in TL2 body (30 minutes runtime). Comparable reflector size (=throw), and a claimed (!) 200 Lumen Streamlight bulb.
Well, I can tell you, the Ultrafire from Emil COMPLETELY BLOWS AWAY the Streamlight. It seems like twice the amount of light!
So I recon: the Streamlight figures may be overdone (probably are), but the Ultrafire can impossibly be much less than 200 Lumen.
If this is the case, three RCR123's give 200 Lumen for 20 minutes, so 4 CR123's can approximately give 250 for 30 minutes (voltage sags more), if the efficiency is comparable.
Having said this, if the Ultrafire can blow away the Streamlight like that, can the Pentagon do the same to the Ultrafire? It's a nice thought, but I am somewhere between hopeful and (close to) sceptical.
Please point out any basic mistakes in this.
Kees