What are the options, anyway -- that forum moderators need to keep track of a second account specially for moderation use?
It is much easier to simply note when they use a green moderation notice, or specifically state that they are acting as a moderator -- and otherwise assume that they are acting as a regular user.
Don't worry -- anyone who's been around for a while knows better than to be afraid of disagreeing with moderators on their off time.
We disagree with them all the time -- they're just opinions.
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All in all, this forum does a good job of maintaining the right balance, or at least I think so.