I find it better if an ally AI is used as a plot device, for example, having a cutscene play then characters from the cutscene that are still in that area, will be stood there once the game starts. Then maybe have an ally 'escort' you , or you 'escort' this ally to a shortish distance away, before you part ways.
Like in half-life having scientists open doors for you.
Not sure if ally AI in x10 is capable of opening doors for you tho, but ey, its a start
-- Game Production has begun! What a long trip it will be... --