Why do people have to be pessimistic about this?
You could simply see it as: so those CFL bulbs grow shit within about a foot of them... So that's 2 feet + bulb width... so if I hang two of those vertically that could cover about 4 vertical feet, 2 foot diameter. I could veg 16 healthy plants to 4 feet with 440w CFL, and throw them under my <insert your favorite lighting system here> to flower.
I'm not saying you have to use it, you should use, or whatever. It's just an idea! Many of the CFL grows I've seen have two major 'fatal' flaws: no reflectors(this alone could account for the yield difference), and less than ideal positioning(solely adjusting plants to the lights instead of hanging/adjusting the lights, and bad fixture design, poor reflectors, etc.).
CFL's give tighter vegetative growth. I've never implied one light(bulb type) is the end-all-be-all of indoor growing. Use what works best for your situation -always.