From what I understand of the whole "Yankee" thing- it was a bastardization of "Jan Kaese" (Jan Cheese) referring to the Dutch of New York (New Amsterdam).
While living in Europe, I was often referred to as "Yank". The only time it bothered me was when there were more than one of us "Yanks" being referred to. BTW- I am a Southerner (a Virginian to be more exact) and as a Southerner, you must have pity on those poor, benighted, ignorant souls who lack the subtle grace to distinguish a person of substance and merit from a scalawag, simply because they share a common passport.