no actually the heirloom is more acidic than the regular navel i think, it has a cleary tanginess almost like a vitamin c chew, but then it has another separate range of perfumes. a bit like the blood orange, but blood orange is a different perfume. this perfume is more like... orange crush hahaha. well, more like what crush would like to be. the platonic ideal of orange crush
i still love the blood orange best, but this heirloom is now in contest with the cara-caras for my second favorite. you're near italy so the blood oranges should be at hand...
as for these heirlooms, i should zest them before peeling... then use the zest in some tasty bake or beverage.