Include a Bandwidth metre - download a file in the background to gauge the users BW
Have a good UI with a graph that allows you to manage how much bandwidth each torrrent is getting and how that affects others.
- If you are really desperate to get one file then prioritse % total bandwidth rather than H/M/L
- Know when to pause downloads as they are interferrign with your priority download
- Allow topause for a until a condition is met - either time, bandwidth available.