As far as I know, At&t does not throttle torrents, so your speed will be the max as long as seeders upload that much.
However, At&t are planning on imposing a bandwidth cap, meaning when you go over the cap, you pay $1 per extra GB. This is starting at reno, but will move to one more market before the end of this year. These caps are extremely low, starting at 20GB at the express level, not to mention there are no unlimited cap plans.
