I had a PM conversation with Clinton - I have recently been thanked for posts by people (including Clinton), really for info I sent by PM at the same time, and frankly those thanks looked a bit like an "old pals network" might be building, because the posts involved only showed part of the info I was thanked for.
Clinton suggests that in the circumstances of getting help via a PM, it might be better to add to the person's reputation by clicking on the star at the foot of a post. He also says he thinks the scoring scheme for the reputation "green blobs" is probably set too high, so he's looking into that.
I can't say that it worries me too much how the things tot up, but I don't like the idea of the thanks system looking like anything cliquey, or an old pals network.
So - reach for the stars ...