Last micro grow I had is with 78w 4000k Philips LED bulbs and 8w 660nm supplementary light. 15 plants in party cups grown 11/13 from seed in 1.6 sqf. ended up with 1g/w.
I think it was Reiko (?) in his workshop thread recently mentioned pushing around 40 watts with his new kit. If you follow along there, results should show over the next run.
Actually I was surfing through some threads looking for the sqft and light watts others are using, to see if someone is close to what I was asking.
What do you know? Blynx himself was been close to 50 watt/sqft all along on one of his cabs. In his "Led micro cab" the one with 8 bulbs, he uses 8 x 10 watts = 80 watts over a 1.74 sq ft area, resulting in 46 watts per square feet.
So yeah, once I have more experience with the cab as it is and I'm better at controlling the canopy height, I might get more light in there.