http://i2pforum.i2p/viewtopic.php?p=2842
With 2 hops, it needs 2 I2P nodes worldwide. It is not easy to put this in numbers and say: 2 hops is just XYZ percent less secure". For our parts, 3 hops are the sweet spot between security and speed and usability. Security & anonymity comes with a price tag, and even 3 hops is not complete 100% secure.