>I’ve found face to face communication effective for resolving contentious disagreements...
I have observed the same. But 9 out of 10 times, it was because the losing party couldn't spend much time thinking about counter arguments.
So again, it cures the symptom, but it benefits only the person with the loudest voice in the room, and not the one with sound reason.
>People seem to understand the other side’s perspective more fully and confusions that can show up in email from things like poor word choice can be resolved...
Don't buy this either. As I said before, the "seem to understand" bit might come from the fact that people often does not express disagreement in face to face communication that often, because they didn't have time to think it through.
EDIT: This is assuming that the both parties in the discussion are more or less on the same level of competence. If the communication is going to be mostly one sided, then face to face communication (Like a teacher in a class room) is fine.