That is a limit I personally would not cross. It's bad historical science to give preference to the witness of biased interpreters dettached from from the original facts by centuries instead of primary sources and allowing the directly involved parts to define the original dispute. *That* line of thought sound to me a lot like "we'll do it regardless of facts".
The whole another thing is that we might learn that Tradition can be expressed in various ways or that the Heterodox doesn't necessarily believe what we have assumed them to believe.
I think you have a point re: our "biased" interpretations today detached by centuries from a particular situation, primary sources, original parties, etc. There's an "ignorance" in the air these days that takes a lot of things and just assumes we know better than our forbears did, and I think that's dangerous, especially if it leads to "we'll do it regardless of facts". But I also think it's dangerous to just maintain the status quo with the blind faith that "they knew what they were doing", presuming that later generations are always and everywhere "worse" than those that came before.
Since the EO/OO split was brought up in this thread, I'll use that as an example. We could simply maintain the current state of affairs and trust that our fathers knew what they were doing and let it be. But to maintain this, I think both EO and OO have to ignore some "inconvenient truths". So I think it's useful to dialogue and try to get to the bottom of things, and I don't think it always and everywhere leads to syncretism. By all means, let whatever documentary evidence is out there help us define the original dispute, as you say. But I don't think it's all a bunch of false assumptions to point to lingustic differences: even if all parties are writing in Greek, they're not all "Greek" in culture or understanding. It was a lingua franca, like English is today, and while forms of English around the world are recognizable as English, we admit that something said in "Indian English" would have a different meaning when understood in "American English"...so I don't think the language thing is so easy to dismiss just because much, if not all, writing was done in Greek. Also, while it is useful to use the primary sources to reconstruct the original dispute, it was clearly more than a literary disagreement. I don't think it's a hyper-ecumenical cop-out to consider the original context of the dispute, with the interaction of factors like differences in cultures, politics, biases (not just a modern phenomenon!) and human sinfulness. Our distance from the original situation, while presenting us with certain handicaps we need to "correct for", also allows us to look at it with an amount of dispassion that just could not apply back then. That doesn't make us "better" or "worse" than our forefathers, it just puts us in a place to see with a fresh set of eyes, if we want to.