Perhaps we would learn more about such debates if we explored why the discussion took place...
Someone felt it was vitally important to do something, someone else felt it was vitally important they did not.
...and why it seemed impossible to reach a conclusive and definitive answer
Because they felt their positions were vitally important.
than if we simply reenacted the same debates with the same sense of ultimate futility. I find that fruitless.
New information has been presented. The same old futility persists.
After all, white southerners could have embraced the rhetoric of revolution and self-determination (with careful qualifiers given their embrace of slavery). They did not.
From the moment slavery breached the tipping point, there were those, only a few prior to the conclusion of the ACW, who realized there was no good way to promote a struggle for the preservation of slavery. Especially via the MORAL right to revolution for JUST cause.
Both sides sought not only to state a position grounded in an understanding of the Constitution, but also to persuade the other side of the legitimacy of that position. Both failed in the latter objective.
Neither were trying to persuade the other side. They were appealing to the undecided. And of course the arguments continued into and beyond the ACW itself, right up to Sept. 12, 2019, with no end in sight. If you're looking for information from which you can determine who was right, you can get it from one party, or the other party, or seek it independently, as best you can, with as little baggage as you can manage. It will probably take a bit of all three.
Yet the need to render political and policy issues in the form of constitutional debate fundamentally shaped that discussion. There were other options, especially for white southerners seeking separation.
Like what? Who can support a struggle to preserve slavery? Accentuate the positives, eliminate the negatives.
Let's put it this way: what if, in 1859, a constitutional scholar unearthed incontrovertible evidence that secession was indeed unconstitutional, at least as presented by secessionist advocates. Would advocates of secession have given up their quest for independence? Would they have found the threat of a Republican victory in 1860 any less menacing? Would they have acted differently in any significant way?
Advocates? No. No. And no.
Potential followers? Depends on the evidence, and the who.
And what if today, another constitutional scholar found incontrovertible evidence that secession was (or was not) constitutional as of 1859? What would that change? How would it reshape our understanding of the past? Not at all, I would say, because the people at the time did not have that knowledge or that evidence