5D Mark III Sea & Sea MDX-5D or Nauticam NA-5DMKIII

Getting quotes for my setup but am confused now should I get the 5D Mark III Sea & Sea MDX-5D (cheaper and lighter) or Nauticam NA-5DMKIII and why?
Here is one reply I had but am not really understanding what is meant by the bulkhead of Nauticam being sealed?
Sea & Sea have some issues with the design (sync cord connection in particular). We have had much more success with Nauticam... Sea & Sea only has one bulkhead for flash cable attachment, and the design is set up so that if it were to fail water will come directly into the housing. Nauticam comes with two, and the bulkheads are sealed so a failure there would protect the camera.

To me they both have the bulkhead mounted on the top, how is the Nauticam sealed vs the one from Sea and Sea?
Thanks anyone.