I wouldn’t know. I don’t know anything about the XP-statistics that you mention, because XP really doesn’t matter to me.
“The bottom line™” about this oughta be real simple: participate, as long as you think you have something meaningful to say in a particular conversation, and don’t fixate on XP. If you really like a post, be sure that you’re logged-in as yourself and “shower it with blessings.” And if you don’t, I suggest, don’t say or vote anything at all. (“Speak well of him, or speak not of him.”)
It is unfortunate – most unfortunate, in my humble – that PM does not appear to tally upvotes and downvotes separately, and that it does not allow you to Super Search using that criteria at all. As I’ve vainly suggested before, it would be very helpful to me to filter posts that, say, at least 2 people thought were beneficial, and no matter how many naysayers there were or weren’t who disagreed with that opinion. I’d consider it more likely that those posts were ones that I should read first, if I’m looking for a particular obscurity. Unfortunately, AFAIK, this criteria cannot be used in filtering. So to speak, it feels good (or not), but it doesn’t do any good.