I suppose the Oy versus Oh pronounciation is similar to any country or area location with accents and pronounciations.
You have Drawls, Midwest, Southern, Brooklyn, Boro Park (kidding!)and at the same time you have English, Queen’s English, Estuary etc.
People will always strive to imply their regional accent is the correct one, the original one, the most eloquently ennounciated and so on so I guess the Oy versus Oh is much the same.
But, in the end does it make us any better of a person? Methinks not. Who really cares? I’ll tell you – only the person who thinks he is better than the next man.
The awful thing is that many a shidduch is based on the Hebrew accent or pronounciation of the boy/family. Sad.