thats a nice light duall!!!! i got a 120watt 6400k light and i use it for flowering with little cfls of 2700k all around as well and it works great been getting nice buids with mixed CFL lights but if ya can got dual thats even better change it like 2 3 weeks into flowering
you will get much better results if you go with a 400w hps. . if thats not an option go for a 8 bulb t5. youll get much better light distribution and you can put it very close to your canopy. i have a friend that used to use strictly mixed spectrum t5 fixtures and he would pull as much as with a 600w.
None of the CFLs used in these arrays is more than 23 watts and smaller ones work fine. These produce a lot of light not just straight down from the top but also from the sides, making this an ideal approach to making bushy little shrubs that are ready to blow up as soon as they hit the bloom room. In my opinion, when flourescent lighting wattage gets much more than 50, it's not efficient for growing plants because the light intensity drops off too quickly as distance increases. The array solves this problem, which is why it promotes better growth.