whats more important than the lumens is what spectrum cfls you have you should get one set of daylight cfls or cool white for flowering and i forgot what the other ones were called but anyways it is generally better to have a better light spectrum than more lumens
and you should check how many lumens per foot you are getting ... for ideal results you should have atleast 2k lumens per foot in vegatative state and 7k lumens in flowering i use 2 400w hps HIDs for a 4x2 feet area with 8 plants so thats like over 11000lumens per foot and per plant and like 100k lumens al together and my babies look really healthy