Despite the fact we seceded from England and did so after issuing a Declaration that justified same in part on the necessity to have the “consent of the governed” and that “ whenever any form of government becomes destructive to these ends, it is the right of the people to alter or to abolish it”.
Indeed between 1803 and 1815 there were no less than three separate public debates on some of the states in New England seceding.
Historian and scholar Thomas DiLorenzo has an excellent lecture on this exact subject. It is available for free download from the Mises.org website:
Yankee Confederates: New England Secession Movements Prior to the War
Between the States
link:
http://mises.org/MultiMedia/mp3/Secession95/10_Secession_DiLorenzo.mp3
While secession may not be a valid Constitutional concept it is preferable to revolution. Revolution would require a true civil war (two or more factions fighting for control of a single government) that would be extremely destructive. In addition, the winning faction would be required to purge the losers of all their leaders and most of the fighters by imprisonment or execution to prevent further insurrection.
If the winners were Obama's communist regime, what's left of the country would become the 21st century version of Stalin's Soviet Union.
On the other hand, one could argue that the institutional violation of any part of the Constitution invalidates the entire Constitution thereby leaving the individual states free to choose their own path via secession.
One needs only go to the Preamble to find the most egregious Constitutional violation that the impending socialist/communist regime will inflict upon the People: "and secure the Blessings of Liberty to ourselves and our Posterity".
Everybody knows that individual Liberty is not high on the list of priorities in a socialist/communist controlled government.