Star Wars: Clones of War will add the vehicles and the soldiers of the Grand Army of the Republic and the Droid army of the Confederacy of Independant systems to Men of War.
When fighting in the early stages of the war, all phase I-clad clone troopers have a mobility disadvantage when compared to the light and speedy B1. The cumbersome phase I armor makes up for it in durability and its flaws are eliminated in the lighter, yet equally durable phase II version of the armor in the closing stages of the war.
In other words, don't get greedy when taking up early positions or this could happen to you too, trooper!