Well, Kunze is one of the places I would have pointed you to - as well as the IBD material, Brewing Science and Practice, the Handbook of Brewing and a bunch of other sources as well.. but I am too late. Apparently not giving you references within 24hrs or so renders my reasonably educated opinion mere hearsay.
Excess copper is toxic to yeast; in lesser amounts affects fermentation performance, catalyses oxidation reactions in hot wort & beer, inhibits enzyme activity, may cause gushing and I seem to recall (but am not sure) can contribute to haze formation - it is necessary in trace amounts... which is why some brewers with all stainless systems will add a small amount of copper into the pipework, although most brewers with all stainless systems don't.
Now I cant be arsed going back over all my study notes to track down exactly which text mentioned it, but if you care to display any faith... take it on faith that I have indeed read that an all copper boil kettle will raise the levels of copper in your wort above optimum levels. Not that it will wreck your beer, not that you cant brew with a copper kettle - just that it isn't optimum.
So IMO copper is a less than optimum choice - But that doesn't mean your Copper vessels wont be ultra cool, will no doubt work a treat, you will have a blast making them and I bet you brew fine beer in them.
Just trying to offer a variety of opinions so you can make an informed choice.
