Alcohol depletes B vitamins and dehydrates the body. That combination of factors gives you the hangover. Also responsible for the DTs (delirium tremons) alcoholics suffer. Other reactions to sugar content, or allergies to sulfites are not related to the alcohol.
Oh yes, I am very well aware to hydrate, as well as replace B vitamins to avoid a hangover (In addition to watching the quantity consumed). We covered this part about the blood/brain barrier thoroughly in neurology class.
Like I said, I have no idea what is/isn't in organic wines that would lessen the effect of a hangover not having tried them. I suppose that with the reasons you listed above, given enough, that theory might be challenged.
cheers!