If you really want to stick with CFL's u would be better with 2x 300w or 4x 150w than 1 600w, you can spread them out then and have better light coverage all over your plant. IMO you would be better with a 250w hps (get a dimable ballast then u don't need to change if u want more power). You can put CFL closer to the plant than a hps, but with the extra lumen output of the hps it still gives your plant more light from 1 foot away than the CFL at 2". CFL's also put out a lot of heat, they just have more surface area to dissipate it, so they both have the same impact on your grow room temps. any ventilation you have that can deal with the heat from your CFL should be fine with a 250w hps imo.
Your plant looks ok though and I hope you get what you want off it