GFXBench's image quality results aren't even necessarily a measurement of the quality of the rendering occurring during any of the performance tests.
And if the difference between Odin's G6430 and Apple's says anything it's that characterizing the IQ of a graphics architecture from GFXBench's results isn't so meaningful, let alone trying to attribute it specifically to the inclusion of FP16 units in addition to its FP32 units (which obviously never made sense anyway.)