Chopjock - we were talking in the context of being in the mountains where there isn't anywhere suitable to land so getting to the point where you are forced to hover taxi in limited vis means you made the wrong decision some time previously and should have turned back or landed then.
Nigel - I think I get what you are saying but why would you hover taxi in 50 -100m vis? Just don't go flying. As per the previous paragraph if you are forced into hovertaxiing in such ridiculous conditions then you f**ked up making your decisions about continued flight earlier in the scenario.
Having done many planned and unplanned VFR to IFR aborts, I agree with DB, not something you take lightly.