The problem with introducing even a little bit of moderation is that it changes the entire thing, really.
First, you need consistently active moderators to read just about everything.
Moderators aren't on the same level as members, especially when they have to make a stance on something.
Moderators can be right or wrong, and no single person can rightfully judge if another person is right or wrong.
Also, in the long run, things can get out of hand permanently. Bear with me as I explain a little bit about the "Standards and Discipline" concept. Fair supervisors (this in a way includes moderators and administrators) need to set clear, objective, measurable, and achievable standards for those they supervise. If any of the subordinates do not meet these minimum standards, something is wrong in the system. If the standards are good, then it's right to discipline or correct the subordinate. If the standards are corrupt, then unnecessary discipline will result, causing permanent damage to cohesiveness. A bit about discipline is that if it is NOT carried out, it will become less effective or cause other problems such as the perception of weak leadership, favoritism, and empty threats.
It may seem irrelevant, or a bit too in depth, but... think about it. Think about if something did go wrong, and how much damage that could cause to the community. Realize how easy it is for a moderator or admin to fuck up, especially when things get heated.
Now, I'd like to offer an alternative to those who would like to see a bit more moderation. When you have a "problem member", the vast majority of the time they do not realize it. Problem members do not constantly question themselves, and shouldn't as it's very unhealthy (these are those who don't take a firm stance on anything thus go with the flow too much). They may become such a problem and resistant that they appear to be malicious, and labeled to be a troll. Very very rarely is this their intent.
These people do not know that they are a problem to the community. They may well know that one or two people strongly disagree with them, but they see nothing wrong with that. They don't, however, know that many more people disagree with them, that many people are losing respect for them, or that they are annoying to all those who are silent.
Speak up! Call them out! If there's a problem member, let them know what they are doing to the community. And I encourage those who agree to do the same, because one person calling them out will just make an ass of themselves (even if it's a moderator or admin). We are not a community that prohibits this kind of behavioral correction. There are far too many communities that do this, thus the problem member never gets corrected, and the behavior gets worse.