Gothichome wrote: . . .that copper puts your slate roof over top of any I have seen
The alternative was aluminum, which just didn't seem right and wouldn't look good over the long term, I think (see next comment). The copper wasn't that much more expensive, relative to the whole job, because most of the cost is the installation not the material; the installation is about the same, maybe a little less for aluminum.
In four or five years when it starts to develop verdigris
Hold on there, cowboy -- move your brain into slate roof time (like tree time, a longer frame of reference than what humans typically use). It takes 2-3 years for the copper to turn brown not shiny, and 15-20 years before it starts to get the green patina. I have copper on a shed roof over my garage doors. It was installed 15 years ago and still hasn't a trace of green. It gets less weather than the copper on the roof will; even so, it's possible I will never see verdigris on my roof. (I hope I last long enough . . . )
I am very curious to see how long it takes before the slate starts to weather and we get some buff/brown/tan tones in the roof. I think it will be a few years but don't know for sure. In 30 years or so the roof will look as it should -- slate roof time.