Studs on slate are not so good in my experience, they do slide until they come to a ridge , channel or lower layer of slate , then they either almost stop the slide, interupt it, or just do nothing at all .
TBH I just wear my Berghause walking boots with good solid vibram soles which are good enough for my needs .
Years ago I had a pair of Zamberlaine
4 season boots which were the best I have ever had expensive but well worth it , but cannot now find an identical pair . No idea what the soles were made from but I have never since found anything to compare with them .
Not thought about getting a new pair of Zambos as I have a pair of Berghause and a Pair of Brashers to wear out first.
Dave