I love
Ivan. I pronounce it EYE-van, but I like the Russian pronunciation too. The former would go over better outside of Eastern
Europe, though, because of the latter's similarity to
Yvonne. I never really got the appeal of
Ivo. It always seemed kind of incomplete to me. I'm pronouncing it EE-vo. I'd use
Ivan as it is, and if I did use a nn, it would be
Vanya instead of
Ivo.