It's too bad espionage is so limited. Imagine this: based on the # of spies you would expend you could commit different acts.
5 spies = sabotage of 1 structure
10 spies = sabotage of 3 structures or lower moral significantly, or invoke a revolt
15 spies = bomb a planet and destroy 60-100% of everything on it
20 spies = bomb it and leave it's PQ permanently altered
Something along these lines would actually make spies and espionage as a main way of playing a viable strategy. Throw in stealing tech, sabotaging ships, getting them to mutiny etc.
I miss the Darloks.