+1 to ratio being minimally important, if at all. Any brewer should obviously tailor their water chemistry to their own preferences. Having said that, the "found a statistically significant negative correlation between the intensity of hop flavor and level of sulfate in the brewing water" quote is directly opposite to my experience and others, I'm sure. Try brewing a hoppy beer with no gypsum and the exact same recipe with a moderate amount of gypsum and compare. I would say it's a fairly positive correlation.
EDIT - Hop bitterness is noticeably enhanced by sulfate as opposed to hop flavor per se, but I've always felt that, by making the beer drier, overall hoppiness is enhanced with sulfate.