Not a scientific, but a practical performance comparison between the two wideangle lenses.
Conclusion: The winner is the Konica Hexanon lens.
Optical: Both lenses deliver a good picture quality, but the Vivitar never reach the sharpness of the Hexanon.
Mechanical: The Hexanon is very compact, while the Vivitar is quite bulky with it's large diameter front lens.
Equipment: Konica T3n, Fuji Reala 100, Manfrotto 190 Tripod, Mirror and Aperture prefire from the Self timer, cable switch.