Like some others on this forum I appreciate you rehashing these topics. Since we lag 6-12 month behind your plan, this way we can comfortably see, how the discussion turns out and and have a current reference for a "state-of-the-art" refit. Could you do another one on "toilet refit" as well? :-) Vacuum, Composting, Electric, ... That is even more complicated than picking the right material for the sails...
To start with the usual useless non-generalizable anecdotes: I painted over the copper coat on my current _daysailing_ boat, because it didn't work in our harbour at all without constant scrubbing. :-) But I think that if you accept having to scrub the boat every now and then, there is nothing better than copper coat. That stuff is so slippery and hard, that cleaning was a very simple affair. Only doing it in the cold water in the Baltic was no fun.
I switched to one of the antifouling systems used for "the big boats": a self-polishing product from BASF called Relest Marine Ecoship. Comparable products are available from others as well. These are based on a PVC-Vinyl primer - not that I understand the details. For the mediterranean and colder seas you can realistically expect multiple years from one application ( 2 layers last 2-3 years, I think with 3 layers you could hope for 4 years). The stuff really polishes off (gets thinner) and doesn't simply "erode until the chips break off".
Is the full Coppercoat treatment for such a large boat really just 15k USD? I would have suspected that it would be much more expensive, as I read about price of 10k for much smaller monohulls.