Interesting that you posted this. About the time you posted it I was playing the battle of Chancellorsville. I was disappointed in that while the battle went very well for me I was merrily hitting F12 to take some very cool screen shots not realizing I wasnt playing with the steam overlay so F12 did exactly nothing.
In my replay of Chancellorsville it was more bloody then the historical battle. Hookers troops did not route & retreat, they stood & fought; in the end we won the day & while we lost allot of troops it was a more strategic victory then the historical account as Hookers nose was seriously bloodied. Put in historical context while the north had more resources & would be better able to absorb the loss then the south I think the political capital from such a bloody defeat would pay dividends for the south. I believe it would have seriously undermined the war effort with northern sympathies as by this time the north was already war weary & losing resolve. Not saying the south wasnt war weary as well but since the battles were being fought in their back yards they had little choice.
More importantly Jackson was not hurt in my replay & moving forward I believe his personage at GB would have a significant impact on how that battle would have played out.
Anyway was great fun & I enjoy thinking about what the impact would have been of the battles I do in GB.
While I have come to truly enjoy Waterloo I would really like to see us have a MP GB battle now & again as well.