Fluence suggests 20w/ m2 without co2, and 40w/ m2 with co2. Naturally its strain dependent, but your chain hardly gets stronger by making a single super strong link.
But I think you could use 800w per m/2 if you build a sun cloak style system, for 2m tall plants, where most of the light goes to side lighting.
http://www.suncloak.com/
But in any case if your looking for bragging rights, you probably want to drive your f-series strips way softer then you originally planned, and brag about the resulting efficiency,