ditto... i think that you are gonna have some kinda major heat problems man..
cfls put off more heat/watt than HID systems.. you may have to put a fan off the 'light board' blowing across the CFL's to keep heat from building there... they are gonna be close to the tops.. i assume.. and that means the heat is gonna be closer than if you had a 250w HPS. and the HPS would have way better light penetration.. but it you are set on the CFL's just vent the board somehow and you should be fine in my opinion..
-J