nigelh:
what you said was: "You really only need about 50-100m of viz to be able to taxi safely I would have said , on gentle ground . ( this is not a recommendation but just what you could do as part of your finding a safe place to land"
Again, its not going to happen, I don't know what you think the scenario is where you find yourself in thick fog and able to transition from forward flight to a hover in this sort of vis, its not going to happen, especially in a helicopter without all the 'bells and whistles'
I ask again as you have ignored the question, have you ever hovered in 50m vis, and do you actually know what 50m vis looks like? As if you did actually know what 50m vis looks like you would realise what utter toss you are spouting.