This looks pretty neat. I've been using qBittorrent on Windows, but it doesn't really support bulk operations, so I've been writing Python scripts[0] to accomplish what I need. Please, cater to the users that need to idle with tons of torrents open all the time and make it easy to import/export the current state of the torrents loaded into client.
Also, shameless plug -- I work on an open source BitTorrent tracker[1] that was adopted by Facebook for deploying their server software and have been playing around with a framework for writing tracker logic via middleware[2]. If you want to talk about any of the client <> tracker interactions, I'm totally down for discussion.
[0]: https://github.com/jzelinskie/move_torrents.py