The payment provider, Minno, is our primary project--we put together TorrentTraveler mostly as a proof of concept for it. We built Minno with an emphasis on user experience and privacy.
Minno only receives information about the size of the download (1GB, 2GB, etc) so that it can charge accordingly. TorrentTraveler deletes all of of its records for each download after 24 hours.
If you have any other questions/comments about Minno, feel free to ping me at calvin [at] minno.co