“Any discussion of secession which analogizes the Confederacy leaving the Union to the US leaving the British Empire is prima facie worthless.”
You don’t see any parallels? Both were being unfairly exploited economically.
What about the differences? Unlike the revolution, the Southern states not only had representation in government but a disproportionate level of representation in government. Unlike the Southern states, the Founding Father's knew that their actions were illegal and would have to fight for their independence. And, of course, the Founding Father's won their rebellion while the Southern states lost.
Anyone whose economy is based on slave labor doesn't have much right to complain about "economic exploitation."
The colonists broke with the UK because, although they were citizens and taxpayers they were not allowed any representation in their nation's councils.
The Confederates had full representation in their nation's counsels - overrepresentation in point of fact - and they broke with the Union because not everything went their way all the time.
The colonists were asserting the rights of men, the Confederates were being babies.