CEC's are a mandatory build for me on every planet. It's one of those no-brainer builds, considering the 20% morale boost it gives besides not having to deal with spies ever again. (I don't particulary care for the espionage part of the game...)
It's not to hard to get the tech, and early completion nets me a near spy free game... I keep a few spies on hand just in case I get jumped early, but after suffering the same mega event as you mention above I don't leave the homeworld without my CEC's...
spies on 200 planets... ugh. I'd be reloading a save, thankyou very much.
T