not all stone-coated tiles are the same created equal
A corrosion inhibitor coating, such as Aluminum-Zinc, is critical for the long-term performance of the tiles.
Many low qualities manufacturers compromise on this by either lowering the AZ coating or using a thinner gauge metal to make the product cheaper.
STONE CHIP LOSS AND COLOR CHANGE
The BIGGEST single complaint from buyers of cheaper roof tiles is color fade.
MANUFACTURER’S TRACK RECORD AND QUALITY ASSURANCE
You should question how exactly their warranty process works.
See them here