You may or may not have a good connection w/S/Pdif on highe sample rates, depending on different factors. As it's not a recommended standard for higher than 48KHz rates, AES/EBU, the pro standard, is adviced.
AES/EBU, like most digital protocols, supports clock sync pretty well.
Word Clock is adviced when:
-an audio DAW uses more than 3 digital devices
-clock instabilities are present. A dedicated W-C- device should keep everything properly clocked.
You can clock Eclipse on AES/EBU alone.