Currently playing latest SVN - large map/deity/nightmare. The AI was slow to expand in the beginning but became faster in the classical era. I know most civs on the planet (got a lucky break spotting a ship from another continent across 3 watertiles with my tracker) and for a while, I got the message that an AI civ founded another city roughly every other turn. I have 10 cities, 5 AIs are larger than me, largest is 19 cities. I must say that the new education system makes the game much more difficult at the highest level, requiring continual large investments to prevent going negative. It made me fall behind several dozen techs and it is really hard to catch up.