Sean, picture a 6' x 6' square 7-Eleven logo.
It would have at least 6, likely 8 fluorescent lamps in it, meaning anything from 400~600W depending on lamps used.
The same sign using Gelcore Power White, Axiom AXLE7 or our PowerStroke, would range from 100~150W, depending on modules and spacing.
Brightness would be the same, so saying 60~80% less energy is entirely reasonable.
I don't think you can light a double faced 6'x6' sign as bright as daylight lamps with 100-150 watt of LEDs sorry but I'm not buyin' that