I would not trust downloading software such as BES from torrents.
The fact of the matter is that you are looking to use software that will interact with a line of electronic communication that you are going to end up setting with service credentials on a computer. The chance of maladjusted software, no matter how minuscule it could be, is more of a chance than I'd want to risk, just because of the nature of how BES is designed to perform.
Would you feel comfortable knowing that there is a possibility of using faulty software that could be modified to forward messages that contain sensitive data to an unknown location in the WWW? BES from a torrent is a dangerous idea in my eyes.
"He that hath no sword, let him sell his garment and buy one."
Jesus, Luke 22:36
"The deadliest weapon in the world is a Marine and his rifle."
Gen. John Pershing, U.S. Army