If u have about 150w - 200w per plant it should turn out great. I have 1 plant with 8 26w 2700k 2k lumen each and 2 6500k tubes only pushing about 1.5k lumen each in a 4' tall x 2' wide area and my plant is turning out to be a monster. My area is like a triangle and has a huge mirror for 1 of the sides, the mirror helps A LOT!
His sort of right,more watt equas more lumens,im no pro on this as its hard to get your head around but I think a 600watt gives 30.000 lumens there is a correct calculator for it.
Im sure you need atleast 2000lumens to each plant,further away the light the more lumens you lose.
Ive never realy had a problem with stretching but I do use 600watts HPS duel spec lights.
I use a T8 6500k 56watt to start clones,I know that kelving is for flower but ive never ha a problem getting them to 7" is then they go in the flower room 12h and pulled back under the T8 for another 6,then sleep and back in..
I think youl find it cheaper to run 1 600w hps then all them flourescents,I run 3 600watt hps lights an it cost aroun £5 a day or every 2 ay,well it cost around £3 every 12h I have lights on,thats also with household stuff,pc,ps3,plasma,fridge,bubblers,fan,10"Vk and 10" carbon filter 2 4 outlet bubblers..
Its not much more then just using my household items to be honest