question about lightning for SOG in 6' x 6' setup

i was thinking about using 2 600w hps lights with cooling system but what about using 4 400w ps with cooling also ????

any suggestions, i also apologize for my poor english it is my second language...

i want to make a SOG system with 4 different stages each one of one square meter, with 15 days intervals within stages....

also any suggestions about strains and numbers of plants per stage are very welcome

bump, any help ???