You don't have to rely on their opinion. The Tor developers themselves have summarized the known attacks on Tor along with references to published research. Spend a few weeks reading the papers and you can make an informed, expert decision about it. https://lists.torproject.org/pipermail/tor-dev/2012-September/003992.html Also, http://dkn255hz262ypmii.onion/index.php?topic=95305.0