I love Transmission and recommend it to all my friends, but I don't actually use it for torrent downloading anymore. I've started downloading my torrents with seedboxes, and using Transmission as a lowly magnet queue.
For this purpose, it would be nice to allow zero (0) as a value for the "active transfer" limit (downloading and seeding), and have Transmission understand that to mean (stop all transfers, and do not allow any resuming). It would be kind of like Turtle Mode, but even more limited. Does that make sense?