You mean they "possibly" have very little to show for. This article is about bugging other nations, not terrorists. There is a lot of value to the NSA if they can claim they thwarted a terrorist attack. However there is no value to the NSA to declare that they are actively monitoring, in theory, advancements in Chinese stealth research just to prove to the citizens the tax dollars are well spent.
Without knowing more about how the information was leaked and what was leaked there is no way to determine if this particular NSA activity was "worth it" or not.
Without knowing more about how the information was leaked and what was leaked there is no way to determine if this particular NSA activity was "worth it" or not.