The prevailing wisdom seems to be that dry hopping is for aroma only, and effects on flavor are assumed to be a matter of perception. (i.e. smell affects taste)

However, while attempting to "fix" a beer that came out far too sweet, I have been looking into hop extracts, etc. While researching I came across this message:

From a chemical point of view, dry hopping will extract all of the alpha andbeta acids in hops. The humulones, lupulones and other volatile oils areisomerized in the alcohol and water (the alcohol dues most of theextraction). Yes, more aroma and flavor will be extracted, but so willbitterness. We dry hop most of the time to add aroma to the beer, so most ofthe time we dry hop with low alpha acid "aroma" hops. Try dry hopping withGalena, Perle, Simcoe, Challenger, Northern Brewer or other high alpha acidhop. You will get the bitterness!

Is this true? Will using high-alpha hops for dry hopping contribute bitterness?