right now with cfl's you have about 200w and about 16000 lumens.
so it's obvious adding more power from the MH is going to outdo your cfls.
4000K isn't just emitting light in one spectrum, it puts out colors in several spectrums. I've read that 4000k works well for veg but I need to see a chart for your specific bulb. Come to think of it I don't know what the normal range for a MH is. So compare the two and then you can think about either keeping your bulb or replacing it with something possibly more efficient.