I had an idea to slightly change the movement mechanics of Champions and Cavalry. If the distance between the Champions stack and the attacked stack is less than the full charge range, the Champions will move back a few squares (if possible) and then attack with a full charge (not quite full, of course). This shouldn't affect the combat mechanics, but it would give the Cavalry an additional bonus (which they should have anyway, by design). And it would simply look like a cool feature for this unit.