It is a bad road when ice/snow conditions are in play. It makes sense to avoid it when these conditions are occurring, as there are sections unless your on the right rubber, you wont have control of the car, regardless of how good a driver you are.
If i was using the Mountain Road to commute, then i would certainly have a spare set of rims with winter/snow tyres on, the difference is like the Formula 1 cars trying to use slicks in the rain.
It is totally amazing the significant increase in traction that you have when you have winter/snow tyres on, even over ice patches.
In European Countries where there roads that are dangerous when snow or ice is present, then by Law you can only travel on these roads with winter/snow tyres on.
As there are at lease two other significantly safer routes available to motorists, then why take the risk of accident/personal injury to yourself or a third party.
Agree 100%
Since they do not look so different it's easy to underestimate the difference winter tyres make. For the past few years I've been using them from about November to April - even without snow and ice there are benefits when the temperature is less than about 7-8deg.
This is quite an interesting comparison:
Micky