Watch your income; when the number turns yellow, your income has begun decreasing by turn (don't trust the huge number it displays when you hover over it; for some reason I don't think the game can display how much you lose per turn, only how much you gain when you're gaining money)

Question: has anyone judged whether the "Logistics" research advancement is working yet?  I would assume that it would make troop upkeep cheaper, but I haven't noticed any evidence toward this.