Why do I not see anyone growing SOG with CFL?
This is based on reading rather than experience, but from what I gather CFLs don't scale well in terms of cost or setup/maintenance workload. SOG implies a lot of plants. Lots of plants means a large number of CFL bulbs for flowering if you want to get dense heavy buds, as if you skimp on lighting you get airy fluffy buds. A small number of CFLs are cheap to buy, easy to setup, easy to cool and cheap to run. As you increase the bulb count though you increase the equipment cost to the point that it approaches or exceeds the initial cost of HPS lighting, but a single large HPS is easier to wire and mount than a large number of CFLs. CFL hardware maintenance costs are also higher than HPS, as the bulbs are more expensive to replace when they fail (watt for watt) and there are a lot more of them.
A very large number of CFLs is more difficult to cool than a single large HPS, as you don't have the option of vented reflector hoods at a good price point. 1000W of CFLs will produce a lot of heat, but the heat sources will be more spread out and thus more difficult to cool than a single 1000W HPS in a vented reflector. This is especially true if you're talking about a large number of low-wattage CFLs.
As you need to keep the CFLs in close proximity to the plants the amount of maintenace work involved in moving lights or plants every day or two adds up to the point that a single large HPS is more desirable in terms of effort required to tend your grow. Put these factors together and you can understand why many people move away from CFL lighting when they scale up their grow beyond a few hundred watts. The only advantages CFLs retain over HPS on a medium-large scale are that they can be easily used to provide side-lighting, and that less energy is lost as heat, though even those advantages are debatable.
CFLs are excellent in small confined spaces, and great for cloning and vegging as you don't need a lot of watts early on, but for flowering on the kind of scale implied by Sea Of Green a HPS system would probably be the better way to go if you want a nice crop of dense heavy buds.
