Taking a discussion that began on Quick Questions here. https://forums.civfanatics.com/threads/quick-questions-quick-answers.573489/page-202#post-15255013 My issue is the huge jump in efficiency from Envoy to Diplomat, and to a lesser degree for other transitions. This creates a great disincentive to research diplo unit techs in order to to delay the "upgrade". An individual tech creating a disadvantage in and of itself is unintuitive and goes against the design of the rest of the tech system. Currently, the only reason I can tell for this to be the case is to advantage weaker civs in diplomacy. While understandable, the current implementation is very clunky and unnaturally distorts tech paths. I propose tying diplo units only to era (as such to the same scaling as city state yields) rather than to individual techs, and introduce scaling for every era (the jump from Envoy to Diplomat is exacerbated by the lack of a Renaissance-era unit). Scaling cost of diplomatic units based on technology number alone is fine too. The diplo-related techs should feature the unlocking of promotions if needed to put them more in line with other technologies design-wise.