I can see how there seca 900 which has 6 r2 leds can get 900 lumens easily.. R2 can be driven hard and get 200+ lumens per bulb..

Overstating lumens is just part of the game.. The MS light is rated at 900 but actual output is 600-660 lumens.. I am fine with that. I know that the Manufacturer rates the P7 bulb at 900, so that is what people use to market the light..

A lot of it is that most drivers for lights are trying to find that balance of brightness vs. runtime.. If you went direct drive, sure they would be bright but the runtime would stink.