The Milk Carton Kids were for me one of the highlights of the New Basement Tapes (along with Marcus Mumford). I do wish they were a little more like The Everly Brothers than Simon & Garfunkel, but then I’m more of a 50’s than a 60’s guy, and more of a Rocker than a Folkie.
Of course, S & G modelled their harmonies on those of the Brothers (the higher part a third above the lower one), as did Lennon & McCartney. It was when they added George on a third part that they got REALLY good, like The Byrds. The harmonies Brian Wilson wrote for The Beach Boys were far above those of either group, very sophisticated.