Liesbeth Casier and Tom Moerenhout of IISD have written a short paper on the Renewable Energy/FIT case (DS412,426). Basically, they are critical of the AB's "benefit" findings, and think the WTO Members should step in to clarify how WTO rules apply to feed-in tariff programs.
Here's their criticism of the AB:
We do not believe the AB should try to avoid the determination of a subsidy in order to have a “green reading” of WTO law—if that was one of its objectives in the first place. An FIT should be recognized as a subsidy by the AB, and WTO members should guarantee that appropriate policies that encourage a shift to the green economy are safeguarded under WTO law. This is particularly the case as long as carbon is not properly accounted for in electricity generation. The lack of carbon pricing remains the principal obstruction to the uptake of renewable energy and should be addressed as such.
The aforementioned potential carve-out of the subsidy definition created by the AB in its reasoning could very well affect other markets and lead to an increase in inefficient state support for other non-green markets.
I think perhaps their argument could be summarized as follows: FIT programs are important and vital for supporting renewable energy, but the AB's attempts to make sure they could be used were overbroad. The WTO Members should look closely at whether there is a better way to ensure that these programs are permitted.