This is something I don't understand. That is why manufacturers continue to develop/improve two-cell *pistol* lights when, as was stated, you can get 100+ lumens from a single cell. It seems that it would be fairly simple to engineer a light that would be no wider through the body than the head/reflector. In other words, the whole unit would pretty much fit within the width of the pistol.
Unless you're military going door-to-door clearing houses all day (and they use shoulder-mounted arms anyway) who needs more than 20 minutes of runtime? If you are using the light properly (intermittently for short periods of time), 20 minutes is waaaay more than enough.
Come on SF & SL, give us a one cell pistol light. Yeah, I know the holster manufacturers will have to re-tool and hate you, tough. Give us the brightest, smallest, lightest pistol light you can engineer. As LEDs gain effeciency, it's gonna happen anyway. You might as well be on the front end.