First off let me say that overall the moderators here do an incredible job and aren't thanked enough for what they do.^ I participate on a few internet boards, and none have mods consistently as professional and helpful as here. There are a few cases where I disagreed with the way a situation was handled, but ultimately I almost always agree with the decisions.
That being said, I don't quite understand your question. I certainly haven't noticed "much grumbling" about moderation, other than a small group of posters who continuously like to complain about a non-existent issue, IMO. I would be open to new ideas, but I just haven't seen anything yet that both needs to be and can be improved.