This is very interesting, Ian (and thanks for posting), especially since a CA winemaker friend and I had tinkered around with some of what we called "Malbecarone" a few years ago. Didn't work, really, because we didn't have the right variety, and we didn't have the same humidity conditions, and couldn't leave it in vats for four years...
Also talked to a winemaker down in Southern Orgeon (Crater Lake Cellars) that is making a Merlot Ripasso style wine, but haven't had a chance to taste that.
This is all so interesting because the creation of the amarone---and the ripasso method---in the Veneto was driven by the desire to do through technique (intervention and manipulation) what couldn't be done naturally given the combination of climate and variety and farming techniques.
That is to say, the vintners were trying to get a fairly moderate and inexpressive "light" grape, grown in an area that did not lend itself historically to "big" grape varieties, to produce big, massive, silky, intensely flavored and intensely aromatic wines.
Corvina/Corvinone and the other blending grapes in the Veneto simply didn't deliver that style of wine, so the ripasso/amarone (drying and concentration and extended aging in inert containers) delivered what the region lacked...which meant the vintners could have their own version of big,massive wines instead of having to rely on other areas (such as Piedmont and Bordeaux, say).
But it's another thing altogether when you take varieties that tend to be big and expressive to begin with and put them through the same process. And especially so in places like Australia, where I've heard there's no particular problem with warmth and dryness and getting the grapes mature (if not overly so).
So, again, thanks for an intriguing report.