Greetings,
DH for CATIIIB is mainly for you to assess if the Aircraft is properly positioned for AUTOLAND, and it is so low that if you Go Around it will be more a Touch and Go than a Go.
So pratically very little difference between DH or NO DH.
Some guys then will mix up NO DH, (no visual cues required) with I can land with RVR 0 if I have NO DH.
, because 75 Meters is the minimum RVR enabling Fire and Rescue team to reach the Airplane with 3 minutes MAX, in case things turned bad, and/or enabling you to taxi out the Airplane.