Well I think being able to see what posts were given a +1 will not increase how often people post,
Didn't say that, I said the post count feature would do so.
but it will allow people to see the type of posts that they get +1s for and perhaps this will allow them to increase the overall quality of future posts.
This sounds like you're trying to turn the BB forums into facebook. You should see the type of crap I get rewarded for over there.
As for the post count feature, I think that it wouldn't increase spam any more than introducing the +1 rating system. So would be a cool feature and would allow users to see how many posts other users had made, and could be compared to how many balls they have as a way to establish credibility.
So people who were required to post a great deal, like GMs, would have a low "credibility," whereas people who never post, like BB-Forrest, would have a high credibility. I don't see the point.