I think the 6.2 suffers from excessive mass at the valve. Ford designed it with the hydraulic lash adjuster at the valve end of the rocker arm. This means that whatever accelerations it feels from the cam are multiplied by the rocker ratio. It probably has about as much mass at the valve as a pushrod engine.
I like how Mazda did it. They seem to have figured out turbo/DI, "fill for life" transmission fluid, etc. as well.
On their Skyactive engines, Mazda uses a class 3 lever (similar to BMW's 14,000rpm S1000RR design), and a low-friction roller cam follower. But the pièce de résistance is the hydraulic lash adjuster (HLA) at the fulcrum.