You can try the WC, but I still wouldn't be using the Berhingers as master...
I think you really need to run both ADA's like you have it setup right now and track the 16 channels simultaneously.
That is the only time you will have both fully packed data streams coming into the RayDAT and being recorded to Sonar (at least 5 minutes). That will be the proof that it's stable and everything stays in sync and if the ADAT glitches or looses sync or acts strange then that's when it will happen. Then I would look into doing the WC setup.
Just out of curiosity....are both the ADA's Sync Lock LED's lit on their front panels?
Does the RayDAT indicate ADAT is sync locked?