I'm a total newb on this, so take what I say with agrain of thought. Just thought I would drop in 2 cents as this page has been idling at the bottom of the list.
I'm still planing my room and I just have a few plants veggin out right now while I design and setup. I also was wondering on these thigns earlier in my research. There seems to be 2 school thoughts and everyone seems to be split evenly across the board.
So from what I understand, CFLS and flouresents can do the job fine, but it just does it slower than that MH and HPS bulbs. Based on what the Green guy wanted, he didn't need to grow any faster, he just wanted his yield/month and set up for that.
If you want to veg faster, then that seems to be where people are adding the MH lights. I haven't learned yet if there are other beneifts other than speed of growth from using this type of light or not yet.
There defintly seems to be a concensus though that HPS is the way to go for flowering.
From what I understand also, you can go from veg to flower under CFLS, but it will take for ever, and the yield will be very small.