I'd been using a bunch of the lesser clients too since that's all I could find in Cydia. It just popped in to my head to google "bit torrent client iOS" yesterday. Shame it's not more known since it seems to be the most complete client available.
Athough I should point out that to get it to work in the background, you have to use the workaround given in the wiki of the google source project that I linked to above.
I wonder how many good open source apps there are floating around that have no presence on Cydia. Hell, a month ago, I had to download the terminal app from it's project page since the one in Cydia wouldn't run on the iPad 2.