A friend of mine has a Square D QO13040L200G box and a QOM2200VH main breaker to go with it, that he will give me a great deal on. This is a main lug box with the main lug adaptive main breaker. Is this box with the add on main breaker acceptable for residential use? Is there any pros/cons to this set up with the convertible main over a box with a fixed main? Thanks all, again! :)