[Growster...]

In the case of the newer replacements for treatments like Bordeaux mixture etc, I'm afraid I have to revert to an earlier statement of 'follow'the money'.

The new versions will all cost a lot more of our hard-earned cash, and whether they're classed as organic or inorganic, keeping pests and diseases at bay is going to be more expensive!

As far as copper is concerned, it is among other trace elements like boron, or molybdenum, which, when in deficit in the soil, cause such problems as onion tips turning yellow, mottled leaves on brassicas etc. These are minor deficiencies of course, and I'd reckon that a one-fix-treats-all approach is probably the answer, but something to knock blight properly just can't be a bad thing IMHO.