My Diplomacy Designs where, in fact, Civilian ones. With the Civilian sensors i had no luck with communication attempts so i moved closer to the population, that when they got blown up.
I agree that Spy missions are at least dodgy but i dont do that outright, only when the diplomatic angle of attack failed. my most succesfull design was a spy ship without cloak but with a ton of shields, sadly you cant speed up the intelligence gathering. i gathered a couple of points, ran away in a hail of missiles and blew those aliens appart with my battle fleet afterwards.
Blowing up Aliens is what i do in Aurora but i am looking forward to a version where i can negociate peace and ally treaties.
i just wondered if you guys already did succesfull Diplomacy and Spy missions and how that turned out.