NB- euro shake has a big advantage over as[halt in that it’s still flexible in the cold and it doesn’t need adhesive strip to stay down. Thsi was one of the most informed and valuable discussion of the growing choice in roofing, though there was no mention of standing seam metal. NB slate maintainence is a huge cost. Most cities don’t have skilled slate guys anymore, no one is welding copper trim,flashing, and even if ther is a capable guy t is not much competition and costs are very very high. To replace a single piece of slate even on relatively low slope roof will be min of $500, easily !