I think your remarks about the Revolution mod should also be posted on their thread so the modders can look into ways to balance it. Some info that can help diagnose the problems would be the map sizes and speeds you both played with. On a standard map with normal speed the Human player has an advantage as he can easily keep his empire happy and small. A huge map or better the planetary map and marathon or odyssey speed can pose some challenge. Keeping your empire happy won't be so easy as you don't get techs needed for using happiness resources or founding a religion quickly enough to keep up with the growth of your cities.
One other point, happiness is not the only concern with revolution, your cities can rebel if you are going through a financial crisis or if your taxes are high (The percentage of commerce dedicated for money).
In conclusion however, your remarks are still true. The mod is supposed to be balanced for any speed or map size unless it was tailored for specific ones and this should be stated clearly of course.