Write out changes of upload/download to per torrent per user table

[itismadness]

We want to be able to track where the bits of upload/download went for any particular album and who they went to to enable better cheater detection.

[undertheironbridge]

"who they went to" won't be that easy to implement, unless I'm missing something about the BitTorrent protocol. Since the clients only report the total downloaded/uploaded amounts via the announces, there is no way to tell which part of these amounts went to particular users, as the tracker is not involved in peer communication directly.
Unless you mean saving the peers (or, rather, user IDs) selected at the time of announcing for a given torrent, alongside the downloaded/uploaded amounts? That's really the only thing that I can think of, is that what you've had in mind?