some communities copper downspouts &c will not survive more than a few days- they may be targets for vandalism/thievery
top quality copper roofs do not last forever; give them 30 good years to deterioration and all after that is a bonus- no experience with gutter issues
oxides run and stain the structure and can harm vegetation in some (rare) circumstances
repairs (storm damage etc) and renovations can be a problem
downspouts, leaders &c can be expensive and hard to find
joints can be soldered to a leakproof seam
they can be a subtle expression of quality but difficult to distinguish from painted aluminum
military penalties can be severe for waste fraud and abuse
if the price is right and you have the tools and equipment the decision is no decision at all- it's a foregone conclusion