Both forms exist in Poland: Dyszyński is used by over 100 people, Duszyński by more than 6,000. It seems rather unique for anyone named Duszyński to change it to Dyszyński. Even thouhg 'y' can also be a vowel in English (gym, physics, etc.), to some Americans that would appear an even more fomridable and unpronounceable litany of consonants with a single vowel 'i' at the end.
