These pictures show a Natural Slate roof that is bleeding rust. As of today, we are not sure whether these slates will develop holes in them, in exactly the same way as the email picture.
It’s the same roof.
The thing about natural slates is that you CANNOT know for sure unless you have the testing done.
For this particular roof, the omens are not good. All these slates are likely to have been sourced from the same seam of slate, and so if I was a gambling man, my money would be on the roof eventually suffering the same horrible fate.
Hopefully my hunch is wrong, but whichever way it goes, bottom line is – why put yourself in that position in the first place?