Sure they did- any compact that you enter you can leave. The reason the secession didn't work is that military force was used to prevent it. It is not so much that they were wrong, but that they LOST. The outcome of the Civil war had nothing to do with who was wrong, but instead proved the rule of "might makes right."
Having the the same party in control of both branches enhances efficiency? Efficiency of what? The controlling party's agenda?
Yes, we are a populist, socialist oligarchy. That is a small group of people who maintain power through the promise of free stuff at the expense of the other guy. Yet, no matter who is in office, very little changes.
The fact that our government still stands is less a testament to its effectiveness and popularity than it is to the fact that we are a very young country.
One last thought- if we were supposed to have the Government we have now, explain the following to me:
the 10th amendment
explain what Article 1, Section 8 meant when it said Congress had the power: To raise and support Armies, but no Appropriation of Money to that Use shall be for a longer Term than two Years;
Where does the Constitution grant the Executive, or the Legislature, the power to "redistribute wealth?"

