In the game colored troops cost slightly more than equivalent white troops; $23k vs $22k. Why should this be? Colored troops might have gotten equal pay and equal equipment, they might have gotten worse, they certainly did not get better pay and better equipment than whites.
Colored troops have exactly the same stats as other heavy line infantry. A strong argument can be made that Colored troops had higher morale and higher assault value. Because they cared a lot more about the slavery issue and they expected to receive no quarter from the Confederates.
http://en.wikipedia.org/wiki/African_Americans_in_the_Civil_War