Current-Mode Logic Explanation
The main link from your link explains it much more and better: http://en.wikipedia.org/wiki/Emitter-coupled_logic

The EMI reduction is due to less changes in the supply rail movement which is galvanically connected to the signals. This tends to have a much greater impact to the signal than radio waves coupling into the signal channel.

It being differential in nature also lends itself to cancellation of radio waves coupling into the signal path as anything that couples into one line will also couple into the other at about the same amount cancelling most common-mode noise.

Some of the advantages this has over other common amplifying schemes are due to the low-output impedance and the removal of the miller effect unlike standard digital logic drive devices. Digital logic basically has everything setup like common-source amplifiers so the output impedance is high, the voltage gain is high, and consequently the miller-effect reduces high frequency performance.