I agree with much of what Laurna said. Right now, Diplomacy has hit a frustration high with me again and I'm leaving it be. Biting the ears off your parley opponents is not, I'm told, a valid diplomacy tactic.
That said, I will reiterate her words: this is not a bash at the team or at the concept, both of which are just plain awesome. Tweaking is undoubtedly an ongoing process, and I don't envy you guys the task of balancing something so complex so that it's challenging yet not *so* challenging that nobody can do it.
Some sort of 40-75 content other than civic diplomacy, which has way too huge a hit for me to relish being beaten 10 times in a row, would indeed be nice. Or maybe all we need is 40-50 content, to give us a leg up into the same strata as the lower NPCs we can parlay with (who are, that said, very few and far between).