Personally my pet theory (as mentioned in the article) is there's more of an immune system reaction then people think. This would explain some of the difference in hangover sensitively and reactions, plus from my personal "experiments" I've noticed pseudoephedrine+painkiller really clears my hangovers up sometimes, much like a bad head cold. On the other hand, it doesn't work every time making me thing that some hangovers are immune-system based, some acetaldehyde based, some dehydration, etc. Plus there's the effects of the beverages drunk and low level gluten or hops intolerance.
DHM-based (Cheers and Zaca usually) and Zbiotics are the best preventatives I've tried so far; they won't stop everything but I do feel a bit better the next day after taking them compared to without. All three are very expensive unfortunately and none are better than the greatest preventative of all: drinking water throughout the night :) .