The intensity of HID lights allows them to penetrate the canopy, floro's don't do this very well. The problem is that floro's have poor lumen production per given arc area. For example: If you put 4 150w HPS lights up, they will not match the intensity of 1 600w HPS, the difference is that the higher wattage arc burns hotter and far brighter if compared, the same area of the arc on the 150w bulb is dimmer than the exact same area on the 600w bulb (by area I mean like square mm or whatever) The HID is also MUCH cheaper than the floro for a lumen to wattage ratio.

I have seen some good looking crops grown under floro's, so I'm not saying it can't be done, only that the HID will give greater yields; and faster, bigger growth in Veg.

Best of luck

L0rdsOth