I used the friends/foes on /., but never thought much about it. Filtered out a number of vocal nutcases.
But wouldn't this sort of create your own cozy echo chamber, where all opinion is streamlined?
I think it would be interestring going the other way around, a bit like some sub Reddits don't show comment score for a day or two, to not cause self reinforcement in moderation.
Maybe even take it a bit further by anonymizing the commenter's name for a limitid time, could be interesting as the comment would then rely fully on content, not reputation or score feedback reinforcement.