well it depends on how many plants you want to try to grow.
that single 250w is just under the 10,000 lumens per flowering plant that you should have,,its 19,000 intal lumens,and should be 20,000 for 2 plants,
the other thing is if you keep the plants smaller so the bulbs are genrally closer to the plant and so penatrate the foilage,,also getting a good feed and flower stim helps to get the most outta your cfl's.
as you can see from that pic the bulbs actually lower than the one on the right to be closer to the one on the left and help bulster yeild..
if you get the small bulds you need to make sure you are reflecting as much light as possible back to the plants,,
so say you get how ever many cfl's if the lumens dont add up to alot more than what you would be getting with the one big one then its not worth it. that big cfl(250w) runs (in my area and eleecie cost etc) for roughly 3p an hour,,where as when I had 3 samller bulbs,,I cant remember the lumens but was about 100ws from 3 bulbs was costing me abit more,roughly 4.1p and hour,,so thats one of the reasons I switched and also my lumens where about 12,000 which was way to small for two plants under the 3 cfl's for flowering anyway,,lumens can be less for seedling and veg stages..,.,.
anyhow hope that helps,,,