This thread is very interesting. I think a great General would add a great token to the game. A great General would function like a queen on a chessboard. One of the most important pieces. I think this should be echoed in AA. The real question is how would they be generated? I think an IPC purchase is too easy. IN real life, Great Generals cannot be bought. Great Generals rise up by proving themselves in battle. I think this should be reflected in AA.
If it were me, I would have the possibility of a Great General emerging after an epic battle. I would define an epic battle as involving many units. The attacker might receive a great general if he wins a battle beating a certain number of defenders. On the flip side, I would allow a defending player a great general roll if he beat back a certain number of attackers in a battle.
After the battle, the player would roll a die to see if he earned a GG.