The speed is still too fast with anything more than about four units per side. Formations just disintegrate. Part of the problem with disintegration is similar to MTW (only faster.) The issue with MTW was that the AI did a lot of "crossing patterns" where units start to engage, then run back behind other engaged troops to the other side of the line. If you direct units against them they get strung out elsewhere. The AI did this in the extremis with royal cav that would charge in, hit your spear line, then disengage and do this 3 or 4 times up and down your line. How the heck it could disengage I don't know. I rarely could when I tried similar things. With RTW the faster speed amplifies the problem several fold.