i've flowered with 3 1k HPS before... with 72 plants finished height of about 4'.... grown in soil (right in the bag)... got about 3 1/2 to 4 lbs. dry weight. Electric bill wasn't too bad.
i'm working on what u are suggesting at the moment...
my journal of that is in my sig, but i need to see some 'back on track' robust vegatative growth before i flip them to 12/12.
