hehe i have 6 CFL's and im not even close to a 400w HPS =P lol you would need like 12-15 CFL's around 32w each to equal one 400w HPS..
probably off subject by now. but Floro's work just fine big ones Little ones dont matter.., HPS get you caught and rape and pillage your electric bill soo its really a personal pref
HPS also work better according to lumen output but ive seen plenty of 4' MJ plants under 6-12 CFL's doing fine and looking just like a plant thats been under HPS.
you could maybe get a low watt hps more to match the wattage u currently have, like 150 or 250 and then if u still need more lumens can gradually add more cfls. this way the peak in electric will be much more gradual.