Has anybody installed INSPIRE ROOFING SLATE shingle

A client I signed up for a 65 sq. wood shake (10" exposer) wants to upgrade the material using a product called INSPIRE ROOFING. These are a type of factory made slate shingle and also flexible to some extent. This home has a turret on it so the flex is a good thing. Their website shows the install to be quite simple. The question I have is the labor time versus the wood shakes. The slate shingles are installed no less than 6"ttw up to 7.5"ttw over 30# felt. No felt layers between each course as with the shakes. Anyone worked with these before? Any tips?-----------------------H