As I see it, the problem with the Imperialistic trait is that it's too dependent on the other leader trait it goes with. Some traits have great synergy with their counterparts, but few are just downright bad.
Julius Ceasar's Imperialistic Organized is no joke. Even without Praetorians, the guy will be a beast at most skill and difficulty levels. His Organized Trait allows his improved settler and warmongering powers to have relevance.
In fact, any UB or other trait that can support a larger empire benefits Imperialistic and allows it to shine. Financial Imperialistic works well, too. The main beef I have with the trait seems to be with Genghis Khan's Aggressive Imperialistic. Once you get to a certain size, you can't make war to expand, and your extra settler powers are likewise useless.
You couple that with a so-so unique unit and a situational UB and you have a Civ that's really poorly representative of a conqueror Civ.
Personally, I would move the Charismatic -25% XP requirement and add it in toto to Imperialistic. That way, there's no question on who's the big daddy when it come to highly decorated troops. It works well with the Military Instructor ability as well as the MA ability, as well as the Warlord ability.
To compensate Charismatic, we include a new power: half anger duration from hurrying production in Slavery and half anger duration from drafting. If the leader is Charismatic, wouldn't it make sense that his people would literally let him get away with murder?
