Answer:
The current system should stay as it is, this system allows for more beneficial cooperation and separation of powers between the states and national government. The current system also allows for less confusion when concerning the delegation of certain powers between the state and the national government, the dual systems finite way of defining where the national government's powers end and where the states' begin. With the current government it's not a fight to figure out where powers begin and end, it is easier to delegate powers because everything is cooperative and not just one singular layer on a cake on top of another layer.
The current system makes the country stronger in relation to the relationship between the state and national government because this current government we have needs the cooperation between the two. With the dual system everything was more separated by a line, which meant that the national government and the state government had little opportunity to truly cooperate in any way that was significant to a strong relationship between the two, except when the concern of delegating powers came into play.
One could argue that the dual system granted for a more clear distribution of powers, it was not as mixed because there was a clear severance between the powers which was more organized. While, yes, that is true, it was always an issue to figure out how to delegate those organized powers, which authority would go to who besides the obvious. With the current system everything is much simpler because it's less of a cleanly organized system and more of an organized mess. This permits a more fluid approach to the situation of the delegation of specific powers and authorities.