250 Watt HPS or 375 Watts of CFL

What would be better for a 2'x2'x4' tall grow box i built? This 250 watt hps system (about 28000 lumens) or 3 of these 125 watt CFLs (about 21000 lumens total) arranged horizontally with reflectors. I will have 9 small plants flowering in this area that were cloned and veged for 2 weeks.
What would be cheaper to run? is wattage all that will factor in to the electic cost? will i have to heat the box if i use the CFLs or will there be enough ambient heat to raise the grow box temp from 17*C to 20*C? Will the HPS system raise the temp too much for my 4" inline duct fan to be effective?

Thanks for any imput.
 
Top