Although I never meant for the runtime plots to measure brightness ( too many factors I have no controll of and or knowledge of), since all but one of the plots (ARC AAA UV) were measured at the same distance, a relative compairison of brightness can be made. On the righthand side of the plot report there is a value for Max measurment and Min measurment. Compairing Max values should give you a relative measurment. Look in the Runtime Archives for those numbers. Doug generally updates the archives every weekend.
http://thelightsite.cruxial.com/revi.../runtimes.html