I guess I will throw some of my thoughts about this into the arena to be given the traditional gladiatorial treatment! :-)
Less XP loss if an old node of yours is down-voted (we forgive you for your old sins). If a node is more than 4 weeks old, then you can no longer lose any XP for it.Doesn't this eliminate the most effective response to plagiarism, as discussed in How should Perlmonks deal with Plagiarism?? Especially given your very own response in Re^4: How should Perlmonks deal with Plagiarism? (legalese). I think a large reason the downvoting response was effective is because of the massive XP loss. I would be curious to hear your thoughts on this matter?
In addition to that:
I get the impression that the effects on low ranking Monks has either not been given due attention or just has not been documented very well. In Re: History now influences voting goibhniu mentions the problem of having a small pool of votes and punishing someone for voting for the same user too many times. And in Re^4: History now influences voting (judgement) dwu points out that users can Vote much sooner than they can Consider, which e.g. raises the question of how they should respond to spam?
It might be nice to have a warning sent to a user's Inbox if he is coming close to exceeding one of the thresholds. This would help negate punishing someone for doing something that is perceived as a community service.
Regarding losing 1 or 2 XP every now and then, there is one situation where it is relevant -- just after leveling up. Maybe a grace period should be put into place before someone is leveled down due to a minor XP loss?
Anyway, just some things to think about.
Oh, and I almost forgot – I think an exception should be made the infamous Paco thread!! :-)