Word Clock is a very good thing to have, to ensure all AD/DA conversions are aligned across your system. ADAT and SPDIF try to include clocks in their protocol, but word clock is worth using whenever available.
wordclock is really a must if you have a number of digital devices to sync, otherwise, if it's just two or three devices, you really don't need it. wordclock should be more jitter-free, if it's used properly.
the sound is better on bnc sync than in adat or spdif sync in scope!(test with digidesign 192 io digital masterclock).
and you can also plug a big master clock like apogee big ben or rosendhal not so expansive now!
it could be a great improvemnent for scope dev plugins or asio recording with digitals AD preamps.
thanks