hey lz near 5000 lumens per square foot over that much space is awesome! bud city
the per square foot question is kind of relative since the number of foot candles that hit our plants is determined by distance from the bulb(i'm sure reflectors cause this number to go up or down.) so over your 5000 per sq. ft. you got some major sweet spots where they're getting way more than that.
my last grow i ended up with 4 ft. tall plants(under a 400 hps). my tops were spectacular but the density was lacking on the lower branches even with good side lighting. i have now vowed not to grow a plant taller than my light will penetrate. so 400... i will now finish at 2 to 2.5 feet at most and i'm adding some nice 30w 6500k 2000 lumen cfls to the mix