The problem is in my mind at the moment, as I always exercise due caution when installing plugins - this one is difficult as I can't see it working. When installing plugins, I follow this approach to keep safe:
1. Download plugin and look at code, to make sure it looks ok and no hidden gremlins.
2. Backup database (files too, if plugin modifies files)
3. Install plugin
4. Do Settings for plugin (if avail)
5. Check its working, and test all functions and output are good.
6. Check error_log to make sure its not throwing errors behind the scenes (some plugins look to work fine, but throw errors and may cause unknown problems)
7. If all is well, I keep the plugin and enjoy, if no, I delete it and restore the database
So you see from the above, why its difficult for me to install and forget - because I may wake up later to find my sites have disappeared or something. I am not happy leaving a plugin active whose actions are not seen and untested.
You say: "It doesn't clear down all transients unless a database update has occurred..."
Can you tell me how to get this "database update" to occur, so I can SEE the immediate results?